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1.
J Am Chem Soc ; 146(23): 16000-16009, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38809420

RESUMO

Constant proportionalities between cells and their intracellular organelles have been widely observed in various types of cells, known as intracellular size scaling. However, the mechanism underlying the size scaling and its modulation by environmental factors in multicomponent systems remain poorly understood. Here, we study the size scaling of membrane-less condensates using microdroplet-encapsulated minimalistic condensates formed by droplet microfluidics and mean-field theory. We demonstrate that the size scaling of condensates is an inherent characteristic of liquid-liquid phase separation. This concept is supported by experiments showing the occurrence of size scaling phenomena in various condensate systems and a generic lever rule acquired from mean-field theory. Moreover, it is found that the condensate-to-microdroplet scaling ratio can be affected by the solute and salt concentrations, with good agreement between experiments and predictions by theory. Notably, we identify a noise buffering mechanism whereby condensates composed of large macromolecules effectively maintain constant volumes and counteract concentration fluctuations of small molecules. This mechanism is achieved through the dynamic rearrangement of small molecules in and out of membrane-free interfaces. Our work provides crucial insights into understanding mechanistic principles that govern the size of cells and intracellular organelles as well as associated biological functions.

2.
Phys Rev Lett ; 133(11): 118401, 2024 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-39331998

RESUMO

The phenomenon of droplet growth occurs in various industrial and natural processes. Recently, the discovery of liquidlike condensates within cells has sparked an increasing interest in understanding their growth behaviors. These condensates exhibit varying material properties that are closely related to many cellular functions and diseases, particularly during the phase transition from liquidlike droplets to solidlike aggregates. However, how the liquid-to-solid phase transition affects the growth of condensates remains largely unknown. In this study, we investigate the growth of peptide-RNA condensates, which behave as either liquidlike droplets or solidlike aggregates depending on the RNA sequences. Dynamic light scattering experiments show that solidlike condensates grow surprisingly faster, with their hydrodynamic diameters increasing over time as d_{h}(t)∼t^{1/2}, contrasting with d_{h}(t)∼t^{1/3} for liquidlike droplets. By combining theoretical analysis and simulations, we demonstrate that this accelerated growth is caused by the noncoalescence aggregation of solidlike condensates and thus formation of percolated swollen structures with a decreased fractal dimension. Moreover, we demonstrate that the accelerated growth can be slowed down by introducing agents that can revert solidlike condensates back to their liquidlike states, such as urea or specific RNAs. Together, our work reveals a fractal-dependent growth mechanism of condensates, with useful insights for understanding the aging of condensates and modulating their aggregation behaviors in synthetic and biological systems.

3.
Langmuir ; 40(40): 21222-21231, 2024 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-39320980

RESUMO

Dynamic wetting in confined spaces is pivotal for the functional efficiency of biological organisms and offers significant potential for optimizing microdevices. The fluids encountered in such scenarios often exhibit shear-thinning behavior, which gives rise to complex interfacial phenomena. Here, we present an intriguing wetting phenomenon for shear-thinning fluids in confined capillary spaces. The employed shear-thinning fluids, carboxymethyl cellulose aqueous solutions with mass fractions of 0.5, 1.0, and 1.5 wt %, exhibit an intermediate state between ideal viscoelastic liquids, viscoelastic solids, and gel-like properties. We elucidate the geometric effect on its capillary wetting behavior, demonstrating that distortion of the moving contact line alters flow dynamics near the front corner, modifying the viscous resistance. This intricate interplay between the modified viscous resistance and the driving force results in a novel dynamic equilibrium distinct from that in Newtonian fluids. We further reveal that the viscous resistance in confined capillaries is controlled by both the morphology of the moving contact line and the shear-thinning exponent, particularly within the range of 0.7 to 1. This novel mechanism provides a pathway for manipulating the wetting dynamics of complex fluids in confined spaces.

4.
Soft Matter ; 20(9): 1966-1977, 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38334990

RESUMO

Plant-based foods are gaining popularity as alternatives to meat and dairy products due to sustainability and health concerns. As a consequence, there is a renewed interest in the phase behaviour of plant proteins and of mixtures of plant proteins and polysaccharides, in particular in the cases where coacervation is found to occur, i.e., liquid-liquid phase separation (LLPS) into two phases, one of which is rich in biopolymers and one of which is poor in biopolymer. Here we review recent research into both simple and complex coacervation in systems involving plant proteins, and their applications in food- as well as other technologies, such as microencapsulation, microgel production, adhesives, biopolymer films, and more.


Assuntos
Proteínas de Plantas , Polissacarídeos , Biopolímeros
5.
J Am Chem Soc ; 145(4): 2375-2385, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36689740

RESUMO

RNA encodes sequence- and structure-dependent interactions to modulate the assembly and properties of biomolecular condensates. RNA G-quadruplexes (rG4s) formed by guanine-rich sequences can trigger the formation of liquid- or solid-like condensates that are involved in many aberrant phase transitions. However, exactly how rG4 motifs modulate different phase transitions and impart distinct material properties to condensates is unclear. Here, using RNA oligonucleotides and cationic peptides as model systems, we show that RNA-peptide condensates exhibit tunability in material properties over a wide spectrum via interactions arising from rG4 folding/unfolding kinetics. rG4-containing oligonucleotides formed strong pairwise attraction with peptides and tended to form solid-like condensates, while their less-structured non-G4 mutants formed liquid-like droplets. We find that the coupling between rG4 dissociation and RNA-peptide complex coacervation triggers solid-to-liquid transition of condensates prior to the complete unfolding of rG4s. This coupling points to a mechanism that material states of rG4-modulated condensates can be finely tuned from solid-like to liquid-like by the addition of less-structured RNA oligonucleotides, which have weak but dominant binding with peptides. We further show that the tunable material states of condensates can enhance RNA aptamer compartmentalization and RNA cleavage reactions. Our results suggest that condensates with complex properties can emerge from subtle changes in RNA oligonucleotides, contributing ways to treat dysfunctional condensates in diseases and insights into prebiotic compartmentalization.


Assuntos
Aptâmeros de Nucleotídeos , Quadruplex G , RNA/química , Aptâmeros de Nucleotídeos/química , Guanina
6.
Ecotoxicol Environ Saf ; 249: 114398, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36508813

RESUMO

BACKGROUND: The endoplasmic reticulum (ER) is a cellular membrane-bound organelle whereby proteins are synthesized, folded and glycosylated. Due to intrinsic (e.g., genetic) and extrinsic (e.g., environmental stressors) perturbations, ER proteostasis can be deregulated within cells which triggers unfolded protein response (UPR) as an adaptive stress response that may impact the migration and invasion properties of cancer cells. However, the mechanisms underlying the nickel compounds on lung cancer cell migration and invasion remain uncertain. OBJECTIVE: We aimed to study whether Nickel chloride (NiCl2) induces ER stress in lung cancer cells, and whether ER stress is involved in modulating epithelial-mesenchymal transition (EMT) and migration by Smads and MAPKs pathways activation following NiCl2 treatment. METHODS: A549 cells were treated with NiCl2 to determine the cell viability using MTT assay. The wound healing assay was used to evaluate cell migration ability. ER ultrastructure was observed by transmission electron microscopy. Western blotting assay was performed to evaluate the protein levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 for ER stress and UPR, E-cadherin and Vimentin for EMT, p-Smad2/3, p-ERK, p-JNK, and p-P38 for activation of Smads and MAPKs signaling pathways. RESULTS: The expression levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 were significantly increased following treatment with NiCl2 in time- and dose-effect relationship. The ER stress inhibitor 4-PBA downregulated the expression levels of the above five proteins, and reversed the decrease in E-cadherin protein level and the increase in vimentin protein expression and cell migration abilities caused by NiCl2. Furthermore, 4-PBA significantly reduced nickel chloride-induced Smad2/3 and p38 MAPK pathway activation, while not affected ERK and JNK MAPK pathways. CONCLUSION: NiCl2 triggers ER stress and UPR in A549 cells. Moreover, 4-PBA alleviates NiCl2-induced EMT and migration ability of A549 cells possibly through the Smad2/3 and p38 MAPK pathways activation, rather than ERK and JNK MAPK pathways.


Assuntos
Estresse do Retículo Endoplasmático , Transição Epitelial-Mesenquimal , Neoplasias Pulmonares , Níquel , Proteína Smad2 , Proteína Smad3 , Humanos , Células A549 , Caderinas/genética , Caderinas/metabolismo , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Neoplasias Pulmonares/induzido quimicamente , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Níquel/toxicidade , Transdução de Sinais , Proteína Smad2/metabolismo , Vimentina/metabolismo , Proteína Smad3/metabolismo
7.
Ecotoxicol Environ Saf ; 195: 110464, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32171946

RESUMO

Nickel compounds are known to be common environmental and occupational carcinogens which also promote the migration of lung cancer cells. However, the molecular mechanism yet remains to be clarified. Hydrogen sulfide (H2S) is involved in cancer biological processes. However, the exact effect and functionality of H2S on nickel, towards the promotion of the migration ability of lung cancer cells, remains to be unknown. In this study, we have found that the nickel chloride (NiCl2) treatment significantly downregulates the protein levels of endogenous H2S enzyme cystathionine ß-synthase (CBS), cystathionine γ-lyase (CSE) and 3-Mercaptopyruvate sulfurtransferase (3-MST). A correlation between NiCl2-induced epithelial-mesenchymal transition (EMT) and the migration ability of lung cancer A549 cells has been observed. Exogenous H2S donor, sodium hydrogen sulfide (NaHS) (100 µmol/L), can reverse NiCl2-induced EMT as well as the migration ability of A549 cells. NiCl2 treatment is able to upregulate the protein level of transforming growth factor-ß1 (TGF-ß1), p-Smad2, p-Smad3, p-JNK, p-ERK and p-P38 in a time-dependent fashion, indicating that both TGF-ß1/Smad2/Smad3 and mitogen-activated protein kinase (MAPK) signaling cascades (a non-Smad pathway) may play essential roles in NiCl2-dependent EMT as well as cell migration of human lung cancer cells. Furthermore, exogenous NaHS alleviates the NiCl2-induced EMT and the migration ability of A549 cells only by regulating TGF-ß1/Smad2/Smad3, rather than the MAPK, signaling pathway. These results indicate that the exogenous administration of NaHS might be a potential therapeutic strategy against nickel-induced lung cancer progression.


Assuntos
Movimento Celular/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Neoplasias Pulmonares/metabolismo , Níquel/farmacologia , Transdução de Sinais/efeitos dos fármacos , Sulfetos/farmacologia , Células A549 , Cistationina beta-Sintase/metabolismo , Cistationina gama-Liase/metabolismo , Humanos , Sulfeto de Hidrogênio/química , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , Proteína Smad2/metabolismo , Proteína Smad3/metabolismo , Sulfurtransferases/metabolismo , Fator de Crescimento Transformador beta1/metabolismo
8.
J Cell Mol Med ; 19(11): 2575-86, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26153045

RESUMO

Cyclophosphamide (CY) is a chemotherapeutic agent used for cancer and immunological diseases. It induces cytotoxicity of bone marrow and causes myelosuppression and extramedullary haematopoiesis (EMH) in treated patients. EMH is characterized with the emergence of multipotent haematopoietic progenitors most likely in the spleen and liver. Previous studies indicated that a Chinese medicine, ginsenoside Rg1, confers a significant effect to elevate the number of lineage (Lin(-) ) Sca-1(+) c-Kit(+) haematopoietic stem and progenitor cells (HSPCs) and restore the function of bone marrow in CY-treated myelosuppressed mice. However, whether the amelioration of bone marrow by Rg1 accompanies an alleviation of EMH in the spleen was still unknown. In our study, the cellularity and weight of the spleen were significantly reduced after Rg1 treatment in CY-treated mice. Moreover, the number of c-Kit(+) HSPCs was significantly decreased but not as a result of apoptosis, indicating that Rg1 alleviated EMH of the spleen induced by CY. Unexpectedly, the proliferation activity of c-Kit(+) HSPCs was only up-regulated in the spleen, but not in the bone marrow, after Rg1 treatment in CY-treated mice. We also found that a fraction of c-Kit(+) /CD45(+) HSPCs was simultaneously increased in the circulation after Rg1 treatment. Interestingly, the effects of Rg1 on the elevation of HSPCs in bone marrow and in the peripheral blood were suppressed in CY-treated splenectomized mice. These results demonstrated that Rg1 improves myelosuppression induced by CY through its action on the proliferation of HSPCs in EMH of the spleen and migration of HSPCs from the spleen to the bone marrow.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Medula Óssea/fisiopatologia , Ciclofosfamida/farmacologia , Ginsenosídeos/administração & dosagem , Hematopoese Extramedular/efeitos dos fármacos , Hematopoese , Baço/fisiopatologia , Animais , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ginsenosídeos/uso terapêutico , Células-Tronco Hematopoéticas/efeitos dos fármacos , Camundongos
9.
J Colloid Interface Sci ; 662: 555-562, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38367573

RESUMO

HYPOTHESIS: Achieving rapid capillary wetting is highly desirable in nature and industries. Previous endeavors have primarily concentrated on passive wetting strategies through surface engineering. However, these approaches are inadequate for high-viscosity fluids due to the significant viscous resistance, especially for non-Newtonian fluids. In contrast, forced wetting emerges as a promising method to address the challenges associated with achieving rapid wetting of non-Newtonian fluids in capillaries. EXPERIMENTS: To investigate the forced wetting behavior of viscoelastic fluids in capillaries, we employ Xanthan Gum (XG) aqueous solutions as target fluids with the storage modulus significantly exceeding the loss modulus. We utilize smooth glass capillaries connected to a syringe pump to achieve high moving speeds of up to 1 m/s. FINDINGS: Our experiments reveal a significant distinction in the power-law exponent that governs the scaling relationship between the dynamic contact angle and velocity for viscoelastic fluids compared to Newtonian fluids. This exponent is considerably smaller and varies based on the concentration of viscoelastic fluids and the diameter of the capillaries. We suggest that the viscosity dominates the wetting dynamics of viscoelastic fluids, manifested by the contact line morphology-dependent behavior. This insight has significant implications for microfluidics and drug injectability.

10.
J Colloid Interface Sci ; 652(Pt B): 2098-2107, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37699328

RESUMO

Hypothesis Although extensive research has been conducted on the dynamic wetting of Newtonian fluids, limited insights have been gained for viscoelastic fluids, particularly on engineered surfaces. We hypothesize that differences in dynamic wetting on microstructured surfaces exist between such fluids, which may be attributed to variations in viscosity and elasticity as well as changes in the microscopic morphology of the moving contact line. Experiments To systematically investigate the wetting differences between Newtonian and viscoelastic fluids on microstructured surfaces, we conducted forced wetting experiments of glycerol-water and carboxymethyl cellulose aqueous solutions on microstructured polytetrafluoroethylene surfaces through a modified Wilhelmy plate method. Findings Results demonstrated an apparent difference in the relationship between the dynamic contact angle and moving velocity with different microstructured surfaces for Newtonian and viscoelastic fluids. The power-law exponent between the capillary number and cubic of the dynamic contact angle increases with the strengthening of shear thinning and elastic effects. In contrast, this exponent is rarely influenced by the scale of microstructured surfaces, particularly in highly viscous regions where viscous force dominates. In addition, viscosity affects the viscous bending and distance that liquid molecules jump at the contact line. These findings have potential applications in coating complex fluids on engineered surfaces.

11.
Nat Commun ; 14(1): 2793, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37193701

RESUMO

Engineering heterogeneous hydrogels with distinct phases at various lengths, which resemble biological tissues with high complexity, remains challenging by existing fabricating techniques that require complicated procedures and are often only applicable at bulk scales. Here, inspired by ubiquitous phase separation phenomena in biology, we present a one-step fabrication method based on aqueous phase separation to construct two-aqueous-phase gels that comprise multiple phases with distinct physicochemical properties. The gels fabricated by this approach exhibit enhanced interfacial mechanics compared with their counterparts obtained from conventional layer-by-layer methods. Moreover, two-aqueous-phase gels with programmable structures and tunable physicochemical properties can be conveniently constructed by adjusting the polymer constituents, gelation conditions, and combining different fabrication techniques, such as 3D-printing. The versatility of our approach is demonstrated by mimicking the key features of several biological architectures at different lengths: macroscale muscle-tendon connections; mesoscale cell patterning; microscale molecular compartmentalization. The present work advances the fabrication approach for designing heterogeneous multifunctional materials for various technological and biomedical applications.

12.
ACS Nano ; 16(6): 9510-9522, 2022 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-35696260

RESUMO

Dropwise condensation represents the upper limit of thermal transport efficiency for liquid-to-vapor phase transition. A century of research has focused on promoting dropwise condensation by attempting to overcome limitations associated with thermal resistance and poor surface-modifier durability. Here, we show that condensation in a microscale gap formed by surfaces having a wetting contrast can overcome these limitations. Spontaneous out-of-plane condensate transfer between the contrasting parallel surfaces decouples the nanoscale nucleation behavior, droplet growth dynamics, and shedding processes to enable minimization of thermal resistance and elimination of surface modification. Experiments on pure steam combined with theoretical analysis and numerical simulation confirm the breaking of intrinsic limits to classical condensation and demonstrate a gap-dependent heat-transfer coefficient with up to 240% enhancement compared to dropwise condensation. Our study presents a promising mechanism and technology for compact energy and water applications where high, tunable, gravity-independent, and durable phase-change heat transfer is required.

13.
Langmuir ; 26(9): 6838-44, 2010 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-20112939

RESUMO

Three functionalized 9,10-distyrylanthracene (DSA) derivatives, namely, 9,10-bis(4-hydroxystyryl)anthracene (2), 9,10-bis{4-[2-(diethylamino)ethoxy]styryl}anthracene (4), and 9,10-bis{4-[2-(N,N,N-triethylammonium)ethoxy]styryl}anthracene dibromide (5), were synthesized and their fluorescence properties were investigated. The three DSA derivatives possess a typical aggregation-induced emission (AIE) property (i.e., they are nonluminescent in dilute solutions but are efficiently fluorescent as induced by molecular aggregation). Different AIE properties were tuned through molecular structure control. Dye 2 is a phenol-moiety-containing compound, which shows aggregation at pH values smaller than 10, resulting in a high fluorescence intensity. Thus, dye 2 has a pK(a) of 9.94. 4 is an amine-containing compound that starts to aggregate at slightly basic conditions, resulting in a pK(a) of 6.90. Dye 5 is an ammonium-salt-containing compound. Because it is very soluble in water, this compound has no AIE phenomenon but can interact strongly with protein or DNA to amplify its emission. Therefore, 5 is a fluorescent turn "on" biological probe for protein and DNA detection and it is also selective, which works for native BSA and ct DNA but not their denatured forms. Therefore, we not only developed a few new compounds showing the AIE phenomena but also controlled the AIE through environmental stimulation and demonstrated that the new AIE molecules are suitable for pH and biomacromolecule sensing.


Assuntos
Antracenos/química , Técnicas de Química Analítica/instrumentação , Corantes Fluorescentes/química , Animais , Antracenos/síntese química , Bovinos , DNA/análise , DNA/química , Corantes Fluorescentes/síntese química , Concentração de Íons de Hidrogênio , Desnaturação de Ácido Nucleico , Desnaturação Proteica , Proteínas/análise , Proteínas/química , Espectrometria de Fluorescência
14.
ACS Nano ; 14(10): 12796-12809, 2020 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-33052666

RESUMO

Droplet transport on, and shedding from, surfaces is ubiquitous in nature and is a key phenomenon governing applications including biofluidics, self-cleaning, anti-icing, water harvesting, and electronics thermal management. Conventional methods to achieve spontaneous droplet shedding enabled by surface-droplet interactions suffer from low droplet transport velocities and energy conversion efficiencies. Here, by spatially confining the growing droplet and enabling relaxation via rationally designed grooves, we achieve single-droplet jumping of micrometer and millimeter droplets with dimensionless jumping velocities v* approaching 0.95, significantly higher than conventional passive approaches such as coalescence-induced droplet jumping (v* ≈ 0.2-0.3). The mechanisms governing single-droplet jumping are elucidated through the study of groove geometry and local pinning, providing guidelines for optimized surface design. We show that rational design of grooves enables flexible control of droplet-jumping velocity, direction, and size via tailoring of local pinning and Laplace pressure differences. We successfully exploit this previously unobserved mechanism as a means for rapid removal of droplets during steam condensation. Our study demonstrates a passive method for fast, efficient, directional, and surface-pinning-tolerant transport and shedding of droplets having micrometer to millimeter length scales.

15.
Lancet ; 371(9629): 2013-8, 2008 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-18555912

RESUMO

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation, and has many components including mucus hypersecretion, oxidative stress, and airway inflammation. We aimed to assess whether carbocisteine, a mucolytic agent with anti-inflammatory and antioxidation activities, could reduce the yearly exacerbation rate in patients with COPD. METHODS: We did a randomised, double-blind, placebo-controlled study of 709 patients from 22 centres in China. Participants were eligible if they were diagnosed as having COPD with a postbronchodilator forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) ratio (FEV(1)/FVC) of less than 0.7 and an FEV(1) between 25% and 79% of the predicted value, were aged between 40 and 80 years, had a history of at least two COPD exacerbations within the previous 2 years, and had remained clinically stable for over 4 weeks before the study. Patients were randomly assigned to receive 1500 mg carbocisteine or placebo per day for a year. The primary endpoint was exacerbation rate over 1 year, and analysis was by intention to treat. This trial is registered with the Japan Clinical Trials Registry (http://umin.ac.jp/ctr/index/htm) number UMIN-CRT C000000233. FINDINGS: 354 patients were assigned to the carbocisteine group and 355 to the placebo group. Numbers of exacerbations per patient per year declined significantly in the carbocisteine group compared with the placebo group (1.01 [SE 0.06] vs 1.35 [SE 0.06]), risk ratio 0.75 (95% CI 0.62-0.92, p=0.004). Non-significant interactions were found between the preventive effects and COPD severity, smoking, as well as concomitant use of inhaled corticosteroids. Carbocisteine was well tolerated. INTERPRETATION: Mucolytics, such as carbocisteine, should be recognised as a worthwhile treatment for prevention of exacerbations in Chinese patients with COPD.


Assuntos
Carbocisteína/uso terapêutico , Expectorantes/uso terapêutico , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Carbocisteína/efeitos adversos , China , Método Duplo-Cego , Expectorantes/efeitos adversos , Feminino , Humanos , Medidas de Volume Pulmonar , Masculino , Pessoa de Meia-Idade , Qualidade de Vida
16.
J Phys Chem Lett ; 6(22): 4566-72, 2015 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-26517760

RESUMO

Advances of optoelectronic devices based on methylammonium lead halide perovskites depend on understanding the role of excitons, whether it is marginal as in inorganic semiconductors, or crucial, like in organics. However, a consensus on the exciton binding energy and its temperature dependence is still lacking, even for widely studied methylammonium lead iodide and bromide materials (MAPbI3, MAPbBr3). Here we determine the exciton binding energy based on an f-sum rule for integrated UV-vis absorption spectra, circumventing the pitfalls of least-squares fitting procedures. In the temperature range 80-300 K, we find that the exciton binding energy in MAPbBr3 is EB = (60 ± 3) meV, independent of temperature; for MAPbI3, in the orthorhombic phase (below 140 K) EB = (34 ± 3) meV, while in the tetragonal phase the binding energy softens to 29 meV at 170 K and stays constant up to 300 K. Implications of binding energy values on solar cell and LED workings are discussed.

17.
Nat Commun ; 5: 5049, 2014 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-25266869

RESUMO

Organic-inorganic perovskites are a class of solution-processed semiconductors holding promise for the realization of low-cost efficient solar cells and on-chip lasers. Despite the recent attention they have attracted, fundamental aspects of the photophysics underlying device operation still remain elusive. Here we use photoluminescence and transmission spectroscopy to show that photoexcitations give rise to a conducting plasma of unbound but Coulomb-correlated electron-hole pairs at all excitations of interest for light-energy conversion and stimulated optical amplification. The conductive nature of the photoexcited plasma has crucial consequences for perovskite-based devices: in solar cells, it ensures efficient charge separation and ambipolar transport while, concerning lasing, it provides a low threshold for light amplification and justifies a favourable outlook for the demonstration of an electrically driven laser. We find a significant trap density, whose cross-section for carrier capture is however low, yielding a minor impact on device performance.

18.
Chem Commun (Camb) ; 47(23): 6602-4, 2011 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-21573315

RESUMO

Conjugated oligocarbazoles with a 9,10-divinylanthracene core have been synthesized, and exhibit the transition from aggregation-induced emission (AIE) to aggregation-induced emission enhancement (AIEE) behaviour with extending conjugation length; self-assembly of the Cz4 molecule affords nanorings with high fluorescent efficiency.

19.
Nan Fang Yi Ke Da Xue Xue Bao ; 29(8): 1599-601, 2009 Aug.
Artigo em Zh | MEDLINE | ID: mdl-19726303

RESUMO

OBJECTIVE: To detect the levels of serum amyloid A (SAA) and explore the pathogenesis of cardiovascular diseases in patients with obstructive sleep apnea syndrome (OSAS). METHODS: Polysomnography was performed in 80 patients with OSAS and 20 control subjects matched for age and body mass index. The patients with OSAS were divided into mild OSAS group (n=22), moderate OSAS group (n=23) and severe OSAS group (n=35) according to the apnea hypopnea index (AHI). Serum amyloid A levels were measured in all the subjects by enzyme-linked immunosorbent assay for correlation analysis. RESULTS: Serum amyloid A levels in mild OSAS group (1.66-/+0.73 microg/ml), moderate OSAS group (2.72-/+1.12 microg/ml) and severe OSAS group (4.08-/+1.85 microg/ml) were significantly higher than those in the control group (0.66-/+0.59 microg/ml) (P<0.05). SAA levels also differed significantly between the 3 OSAS groups (P<0.01), increasing with the severity of OSAS. Correlation analysis indicated that SAA level was positively correlated to AHI (r=0.649, P<0.01) and TSaO(2)<90% (r=0.491, P<0.01), but inversely yo miniSaO(2) (r=-0.499, P<0.01). After 3 months of nCPAP therapy, SAA levels were significantly decreased in the 20 patients with severe OSAS (4.13-/+2.27 microg/ml vs 5.14-/+2.30 microg/ml, P<0.01). CONCLUSION: SAA levels are elevated in OSAS patients in close correlation to the severity of OSAS, which may contribute to the vulnerability of the patients to cardiovascular diseases. nCPAP therapy help reduce the risk for cardiovascular diseases in OSAS patients.


Assuntos
Proteína Amiloide A Sérica/metabolismo , Apneia Obstrutiva do Sono/metabolismo , Adulto , Idoso , Doenças Cardiovasculares/complicações , Doenças Cardiovasculares/patologia , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia , Apneia Obstrutiva do Sono/complicações , Apneia Obstrutiva do Sono/diagnóstico
20.
Zhongguo Fei Ai Za Zhi ; 11(6): 789-92, 2008 Dec 20.
Artigo em Zh | MEDLINE | ID: mdl-20797330

RESUMO

BACKGROUND: Lung cancer is one of the most common cancers in the world, whose mortality is at the first place in all malignant tumors. This study is to investigate the diagnostic value of ADAM8 and CEA in serum of non-small cell lung cancer patients. METHODS: The serum levels of ADAM8 were assayed by ELISA in 62 NSCLC patients, 27 benign palmonary lesions and 32 healthy subjects as control. The serum level of CEA were assayed by radioimmunoassay. RESULTS: The serum level of ADAM8 and CEA in group of NSCLC were both remarkably higher than those in lung benign lesions and normal controls (P <0.01), without significant difference between benign palmonary lesions and normal controls (P >0.05). There was no significant difference between adenocarcinoma and squamous cell carcinoma in serum ADAM8 level (P >0.05). The serum level of CEA in adenocarcinoma were significantly higher than that in squamous cell carcinoma (P <0.05). The serum level of ADAM8 and CEA in NSCLC with stages III-IV were both remarkably higher than those with stages I-II (P <0.01). The level of ADAM8 and CEA in NSCLC with lymph node metastasis positive were both higher than those of negative (P <0.01). The diagnostic sensitivity of ADAM8 and CEA for NSCLC was 77.4% and 71.0% respectively, and the specificity was 90.6% and 84.4% respectively. The combined detection of ADAM8 and CEA could improve the sensitivity to 91.9%, but the specificity decreased to 75.0%. CONCLUSIONS: The overexpression of ADAM8 in serum of NSCLC patients indicates that ADAM8 is related to the development of NSCLC; Combined detection of ADAM8 and CEA is helpful for the diagnosis of NSCLC.

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