Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 43
Filtrar
Mais filtros

Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Clin Exp Pharmacol Physiol ; 51(7): e13874, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38797519

RESUMO

Glycolysis is vital for the excessive proliferation of keratinocytes in psoriasis, and uridine phosphorylase-1 (UPP1) functions as an enhancer of cancer cell proliferation. However, little is known about whether UPP1 promotes keratinocyte proliferation and accelerates psoriasis development. This study revealed that UPP1 facilitates cell viability and cell-cycle progression in human epidermal keratinocytes (HEKs) by modulating the glycolytic pathway. Bioinformatics analysis of UPP1 gene expression and its correlation with the Reactome revealed that UPP1 mRNA expression, cell-cycle progression, the interleukin-6 (IL-6)/Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway and glycolysis were positively associated with psoriasis. Cell proliferation, the cell cycle and glycolysis were evaluated after UPP1 was silenced or overexpressed. The results showed that UPP1 overexpression increased cell proliferation, cell-cycle progression and glycolysis, which was contrary to the effects of UPP1 silencing. However, the STAT3 inhibitor diminished UPP1 expression because STAT3 can bind to the UPP1 promoter. In conclusion, UPP1 was significantly activated by the IL-6/STAT3 pathway and could modulate glycolysis to regulate cell proliferation and cell-cycle progression in keratinocytes during the development of psoriasis.


Assuntos
Ciclo Celular , Sobrevivência Celular , Glicólise , Queratinócitos , Fator de Transcrição STAT3 , Uridina Fosforilase , Humanos , Proliferação de Células , Epiderme/metabolismo , Epiderme/patologia , Interleucina-6/metabolismo , Interleucina-6/genética , Queratinócitos/metabolismo , Psoríase/patologia , Psoríase/metabolismo , Psoríase/genética , Transdução de Sinais , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT3/genética , Uridina Fosforilase/metabolismo , Uridina Fosforilase/genética
2.
Chemistry ; 27(11): 3574, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33460155

RESUMO

Invited for the cover of this issue is the group of Prof. Dr. Yingjie Zhao at Qingdao University of Science and Technology. The image depicts the ultrathin two-dimensional polymer reported in this work. Read the full text of the article at 10.1002/chem.202004797.

3.
Chemistry ; 27(11): 3661-3664, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33264450

RESUMO

Two-dimensional polymers (2DPs) have attracted much interest due to their unique 2D atomic-thick covalent network with periodically linked monomers. The preparation of mono- or few-layered 2DPs with highly ordered structures is still a big challenge. Herein, we report a preparation of ultrathin 2DP film based on photo-triggered [2+2] cycloaddition at the air/water interface. The pre-assembly process induced by the D-A interactions before the polymerization plays a key role in constructing the highly ordered structure. The precise structure and chemical compositions of the continuous 2DP films were proved by selected area electron diffraction (SAED), Tip-Enhanced Raman Spectroscopy (TERS) and molecular-mechanics-based structural simulation.

4.
Langmuir ; 37(51): 14813-14822, 2021 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-34910489

RESUMO

Adsorption-induced adsorbent deformation is of fundamental importance to geoscientists and engineers. To gain insight into the deformation behaviors of different materials, we presented grand canonical Monte Carlo (GCMC) simulations of methane adsorption-induced deformation in slit pores. Adsorption isotherms and deformation behaviors of the pores were obtained for adsorbents with variations in solid density and affinity. The results showed that the adsorption-induced deformation depends on adsorbate loading, pore width, solid density, and affinity. The deformation at a given adsorption loading could be comparable between different solid densities or affinities because solid density or affinity is related to the solvation pressure as the driving force behind the deformation and also the resistance of the deformation. The interaction of these two effects controls the deformation behavior. We expect that our results will help to understand the adsorption-induced deformation in solids with heterogeneous properties and estimate deformation using the gas adsorption data.

5.
Langmuir ; 36(48): 14656-14665, 2020 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-33233895

RESUMO

Brunauer-Emmett-Teller (BET) surface area obtained by nitrogen adsorption is a commonly adopted value to characterize the specific surface area for porous materials. In the BET method, the widely applied cross-sectional area of nitrogen is 16.2 Å2, which has been found to be an oversimplified assumption. The adsorption isotherms of nitrogen simulated with the 2CLJ (Lennard-Jones) + 3q molecular model at 77 K was utilized to determine the cross-sectional area and its behavior as a function of pressure, pore size, and solid affinity. The cross-sectional area shows a negative relation with the pressure and varies with pore size and solid affinity. The overestimation of the BET surface area might arise from the inaccurately determined monolayer adsorption capacity and the cross-sectional area.

6.
BMC Genomics ; 16: 793, 2015 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-26470872

RESUMO

BACKGROUND: Long intergenic noncoding RNAs (lincRNAs) are endogenous non-coding RNAs (ncRNAs) that are transcribed from 'intergenic' regions of the genome and may play critical roles in regulating gene expression through multiple RNA-mediated mechanisms. MicroRNAs (miRNAs) are single-stranded small ncRNAs of approximately 21-24 nucleotide (nt) that are involved in transcriptional and post-transcriptional gene regulation. While miRNAs functioning as mRNA repressors have been studied in detail, the influence of miRNAs on lincRNAs has seldom been investigated in plants. METHODS: LincRNAs as miRNA targets or decoys were predicted via GSTAr.pl script with a set of rules, and lincRNAs as miRNA targets were validated by degradome data. Conservation analysis of lincRNAs as miRNA targets or decoys were conducted using BLASTN and MAFFT. The function of lincRNAs as miRNA targets were predicted via a lincRNA-mRNA co-expression network, and the function of lincRNAs as miRNA decoys were predicted according to the competing endogenous RNA (ceRNA) hypothesis. RESULTS: In this work, we developed a computational method and systematically predicted 466 lincRNAs as 165 miRNA targets and 86 lincRNAs as 58 miRNA decoys in maize (Zea mays L.). Furthermore, 34 lincRNAs predicted as 33 miRNA targets were validated based on degradome data. We found that lincRNAs acting as miRNA targets or decoys are a common phenomenon, which indicates that the regulated networks of miRNAs also involve lincRNAs. To elucidate the function of lincRNAs, we reconstructed a miRNA-regulated network involving 78 miRNAs, 117 lincRNAs and 8834 mRNAs. Based on the lincRNA-mRNA co-expression network and the competing endogenous RNA hypothesis, we predicted that 34 lincRNAs that function as miRNA targets and 86 lincRNAs that function as miRNA decoys participate in cellular and metabolic processes, and play role in catalytic activity and molecular binding functions. CONCLUSIONS: This work provides a comprehensive view of miRNA-regulated networks and indicates that lincRNAs can participate in a layer of regulatory interactions as miRNA targets or decoys in plants, which will enable in-depth functional analysis of lincRNAs.


Assuntos
MicroRNAs/genética , RNA Longo não Codificante/genética , RNA Mensageiro/genética , Zea mays/genética , Biologia Computacional , Regulação da Expressão Gênica de Plantas , Estabilidade de RNA/genética
7.
Phys Chem Chem Phys ; 16(24): 12362-73, 2014 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-24826906

RESUMO

A new theory of condensation in an open end slit pore, based on the concept of temperature dependent undulation, at the interface separating the adsorbed phase and the gas-like region, is presented. The theory, describes, for the first time, the microscopic origin of the critical hysteresis temperature and the critical hysteresis pore size, properties which are not accessible to any classical theories.

8.
Yi Chuan ; 36(12): 1226-34, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25487267

RESUMO

Long intergenic non-coding RNAs (lincRNAs) located between protein-coding genes are non-coding RNAs longer than 200 nucleotides in length. LincRNAs are involved in a variety of biological processes such as cell cycle regulation, immune surveillance and embryonic stem cells differentiation in animals; however, the function of lincRNAs in plants is largely unclear. MicroRNAs (miRNAs) are a class of endogenous, single-stranded, non-coding small (~21 nt) RNAs, which can regulate gene expression at transcriptional or post-transcriptional level in eukaryotes by means of sequence complementation. Now, intensive studies on protein-coding genes targeted by miRNAs have been carried out, but the research on non-coding RNAs targeted by miRNAs is seldom explored, especially in plants. In order to uncover the potential function of lincRNAs, the data including miRNAs, cDNAs and degradomes were firstly collected and integrated, followed by bioinformatics methods to predict the potential binding sites of 337 mature miRNAs at 2708 lincRNAs in Arabidopsis thaliana. The regulatory networks of miRNAs-mRNAs-lincRNAs were constructed and the function of lincRNAs was predicted according to the competing endogenous RNA (ceRNA) hypothesis. This study may lay a solid foundation for elucidating the regulatory mechanism of miRNAs on lincRNAs as well as the function of lincRNAs in plants.


Assuntos
Regulação da Expressão Gênica de Plantas , MicroRNAs/fisiologia , RNA Longo não Codificante/fisiologia , Biologia Computacional , Redes Reguladoras de Genes
9.
Dalton Trans ; 53(5): 1977-1988, 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38205595

RESUMO

Most platinum group-based cyclometalated neutral and cationic anticancer complexes with the general formula [(C^N)2Ir(XY)]0/+ (neutral complex: XY = bidentate anionic ligand; cationic complex: XY = bidentate neutral ligand) are notable owing to their intrinsic luminescence properties, good cell permeability, interaction with some biomolecular targets and unique mechanisms of action (MoAs). We herein synthesized a series of neutral and cationic amine-imine cyclometalated iridium(III) complexes using Schiff base ligands with sp2-N/sp3-N N^NH2 chelating donors. The cyclometalated iridium(III) complexes were identified by various techniques. They were stable in aqueous media, displayed moderate fluorescence and exhibited affinity toward bovine serum albumin (BSA). The complexes demonstrated promising cytotoxicity against lung cancer A549 cells, cisplatin-resistant lung cancer A549/DDP cells, cervical carcinoma HeLa cells and human liver carcinoma HepG2 cells, with IC50 values ranging from 9.98 to 19.63 µM. Unfortunately, these complexes had a low selectivity (selectivity index: 1.62-1.98) towards A549 cells and BEAS-2B normal cells. The charge pattern of the metal center (neutral or cationic) and ligand substituents showed little influence on the cytotoxicity and selectivity of these complexes. The study revealed that these complexes could target mitochondria, cause depolarization of the mitochondrial membrane, and trigger the production of intracellular ROS. Additionally, the complexes were observed to induce late apoptosis and perturb the cell cycle in the G2/M or S phase in A549 cells. Based on these results, it appears that the anticancer efficacy of these complexes was predominantly attributed to the redox mechanism.


Assuntos
Antineoplásicos , Carcinoma , Complexos de Coordenação , Neoplasias Pulmonares , Humanos , Antineoplásicos/farmacologia , Antineoplásicos/metabolismo , Células HeLa , Irídio/farmacologia , Complexos de Coordenação/farmacologia , Complexos de Coordenação/metabolismo , Ligantes , Quelantes/farmacologia , Mitocôndrias/metabolismo , Neoplasias Pulmonares/metabolismo , Carcinoma/metabolismo , Apoptose , Linhagem Celular Tumoral
10.
Front Plant Sci ; 15: 1338425, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38571717

RESUMO

The introduction of dwarfing genes triggered a wave of "green revolution". A number of wheats dwarfing genes have been reported in previous studies, and only a small fraction of these have been applied to production practices. Therefore, the development of novel dwarfing genes for wheat is of great value. In this study, a novel dwarfing site, Rht-yz, identified in the Yanzhan mutation, is located on chromosome 4B (30-33MB) and its mechanism of action is different from that of Rht-B1b (C-T mutation), but whether it affects the Rht-B1a (TraesCS4B02G043100) or other genes is unclear. Exogenously applied GA3 experiments showed that Rht-yz is one of the gibberellin-insensitive dwarf genes. The effects of the dwarf gene Rht-yz on agronomic traits in wheat were evaluated in the field using Yanzhan, Yanzhan mutations, F2:3 and F3:4 lines. The results showed that Rht-yz improved lodging resistance by reducing plant height, increasing diameter, wall thickness and mechanical strength of the basal stem. In terms of yield traits, Rht-yz had negative effects on tiller number plant-1, biomass plant-1 and yield plant-1, but had no significant effect on harvest index, 1000-kernel weight and spike traits. In addition, Rht-yz significantly increased crude protein, wet gluten and starch content. Therefore, the rational use of the new dwarfing site Rht-yz has potential and value in dwarf wheat breeding.

11.
Sci Rep ; 13(1): 8833, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37258695

RESUMO

Accumulating evidence shows that pseudogenes can function as microRNAs (miRNAs) sponges and regulate gene expression. Mining potential interactions between pseudogenes and miRNAs will facilitate the clinical diagnosis and treatment of complex diseases. However, identifying their interactions through biological experiments is time-consuming and labor intensive. In this study, an ensemble learning framework with similarity kernel fusion is proposed to predict pseudogene-miRNA associations, named ELPMA. First, four pseudogene similarity profiles and five miRNA similarity profiles are measured based on the biological and topology properties. Subsequently, similarity kernel fusion method is used to integrate the similarity profiles. Then, the feature representation for pseudogenes and miRNAs is obtained by combining the pseudogene-pseudogene similarities, miRNA-miRNA similarities. Lastly, individual learners are performed on each training subset, and the soft voting is used to yield final decision based on the prediction results of individual learners. The k-fold cross validation is implemented to evaluate the prediction performance of ELPMA method. Besides, case studies are conducted on three investigated pseudogenes to validate the predict performance of ELPMA method for predicting pseudogene-miRNA interactions. Therefore, all experiment results show that ELPMA model is a feasible and effective tool to predict interactions between pseudogenes and miRNAs.


Assuntos
MicroRNAs , MicroRNAs/genética , MicroRNAs/metabolismo , Pseudogenes/genética , Aprendizado de Máquina , Biologia Computacional/métodos , Algoritmos
12.
Front Pediatr ; 11: 1102878, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37077339

RESUMO

Background: Moderate-to-severe bronchopulmonary dysplasia (msBPD) is a serious complication in preterm infants. We aimed to develop a dynamic nomogram for early prediction of msBPD using perinatal factors in preterm infants born at <32 weeks' gestation. Methods: This multicenter retrospective study conducted at three hospitals in China between January 2017 and December 2021 included data on preterm infants with gestational age (GA) < 32 weeks. All infants were randomly divided into training and validation cohorts (3:1 ratio). Variables were selected by Lasso regression. Multivariate logistic regression was used to build a dynamic nomogram to predict msBPD. The discrimination was verified by receiver operating characteristic curves. Hosmer-Lemeshow test and decision curve analysis (DCA) were used for evaluating calibration and clinical applicability. Results: A total of 2,067 preterm infants. GA, Apgar 5-min score, small for gestational age (SGA), early onset sepsis, and duration of invasive ventilation were predictors for msBPD by Lasso regression. The area under the curve was 0.894 (95% CI 0.869-0.919) and 0.893 (95% CI 0.855-0.931) in training and validation cohorts. The Hosmer-Lemeshow test calculated P value of 0.059 showing a good fit of the nomogram. The DCA demonstrated significantly clinical benefit of the model in both cohorts. A dynamic nomogram predicting msBPD by perinatal days within postnatal day 7 is available at https://sdxxbxzz.shinyapps.io/BPDpredict/. Conclusion: We assessed the perinatal predictors of msBPD in preterm infants with GA < 32 weeks and built a dynamic nomogram for early risk prediction, providing clinicians a visual tool for early identification of msBPD.

13.
ACS Appl Mater Interfaces ; 15(42): 49701-49711, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37846058

RESUMO

Room-temperature phosphorescent (RTP) liquid crystal materials have garnered considerable attention because of their significant applications in organic light emitting diodes, polarized light emitting materials, and so forth. How to efficiently synthesize pure organic RTP liquid crystals and regulate their performance is of great significance. In this article, we propose a simple and feasible method to synthesize RTP liquid crystals and manipulate their properties through copolymerization. We constructed RTP liquid crystal copolymers by copolymerizing a phosphorescent monomer bearing biphenyl mesogen with a phosphorescent monomer bearing a dibenzofuran chromophore. All the synthesized copolymers show a liquid crystal property because of the introduction of biphenyl mesogen. Meanwhile, by changing the composition of copolymers, it is possible to regulate their RTP performance, including luminescence color and lifetime. As the content of the PMDFM0C component in copolymers increases, the phosphorescence lifetime gradually increases. For poly(MDFM0C(0.46)-co-MBi18C(0.54)), the phosphorescence lifetime can reach 463.0 ms. Moreover, the phosphorescence color of the PMDFM0C component in copolymers changes with the copolymer composition, which can induce variable room-temperature phosphorescence. In addition, when oriented, liquid crystal copolymer films can emit linearly polarized fluorescence and linearly polarized phosphorescence. The linearly polarized phosphorescence dichroic ratio and polarization ratio values of the oriented poly(MDFM0C(0.46)-co-MBi18C(0.54)) film are 3.33 and 0.50, respectively.

14.
Clin Exp Otorhinolaryngol ; 16(3): 282-289, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37475139

RESUMO

OBJECTIVES: We aimed to develop a new calculation model for calcium requirements in dialysis patients following parathyroidectomy. METHODS: A total of 98 patients with secondary hyperparathyroidism receiving parathyroidectomy from January 2014 to January 2022 were enrolled in this study. Among these patients, 78 were randomly selected for construction of the calcium requirement calculation model, and the remaining 20 patients were selected for model validation. The calcium requirement model estimated the total calcium supplementation for 1 week after surgery using variables with significant relationships in the derivation group by stepwise multiple linear regression analysis. Bias, precision, and accuracy were measured in the validation group to determine the performance of the model. RESULTS: The model was as follows: calcium requirement for 1 week after surgery=33.798-8.929×immediate postoperative calcium+0.190×C-reactive protein-0.125×age+0.002×preoperative intact parathyroid hormone+0.003×preoperative alkaline phosphatase (R2=0.8). The model was successfully validated. CONCLUSION: We generated a novel model to guide calcium supplementation. This model can assist in stabilizing the serum calcium levels of patients during the early postoperative period. Furthermore, it contributes to the individualized and precise treatment of hypocalcemia in patients following parathyroidectomy.

15.
Light Sci Appl ; 12(1): 9, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36588110

RESUMO

Multicolor imaging allows protein colocalizations and organelle interactions to be studied in biological research, which is especially important for single-molecule localization microscopy (SMLM). Here, we propose a multicolor method called excitation-resolved stochastic optical reconstruction microscopy (ExR-STORM). The method, which is based on the excitation spectrum of fluorescent dyes, successfully separated four spectrally very close far-red organic fluorophores utilizing three excitation lasers with cross-talk of less than 3%. Dyes that are only 5 nm apart in the emission spectrum were resolved, resulting in negligible chromatic aberrations. This method was extended to three-dimensional (3D) imaging by combining the astigmatic method, providing a powerful tool for resolving 3D morphologies at the nanoscale.

16.
Genomics Proteomics Bioinformatics ; 20(3): 435-445, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-34856391

RESUMO

With accumulating dysregulated circular RNAs (circRNAs) in pathological processes, the regulatory functions of circRNAs, especially circRNAs as microRNA (miRNA) sponges and their interactions with RNA-binding proteins (RBPs), have been widely validated. However, the collected information on experimentally validated circRNA-disease associations is only preliminary. Therefore, an updated CircR2Disease database providing a comprehensive resource and web tool to clarify the relationships between circRNAs and diseases in diverse species is necessary. Here, we present an updated CircR2Disease v2.0 with the increased number of circRNA-disease associations and novel characteristics. CircR2Disease v2.0 provides more than 5-fold experimentally validated circRNA-disease associations compared to its previous version. This version includes 4201 entries between 3077 circRNAs and 312 disease subtypes. Secondly, the information of circRNA-miRNA, circRNA-miRNA-target, and circRNA-RBP interactions has been manually collected for various diseases. Thirdly, the gene symbols of circRNAs and disease name IDs can be linked with various nomenclature databases. Detailed descriptions such as samples and journals have also been integrated into the updated version. Thus, CircR2Disease v2.0 can serve as a platform for users to systematically investigate the roles of dysregulated circRNAs in various diseases and further explore the posttranscriptional regulatory function in diseases. Finally, we propose a computational method named circDis based on the graph convolutional network (GCN) and gradient boosting decision tree (GBDT) to illustrate the applications of the CircR2Disease v2.0 database. CircR2Disease v2.0 is available at http://bioinfo.snnu.edu.cn/CircR2Disease_v2.0 and https://github.com/bioinforlab/CircR2Disease-v2.0.


Assuntos
MicroRNAs , RNA Circular , MicroRNAs/genética , Bases de Dados Factuais , Regulação da Expressão Gênica
17.
Iran J Kidney Dis ; 16(2): 135-146, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35489082

RESUMO

INTRODUCTION: Secondary hyperparathyroidism may cause an increase in blood pressure among maintenance hemodialysis (MHD) patients. The objective of this study were to observe the effects of different treatment modalities of hyperparathyroidism on blood pressure among MHD patients with secondary hyperparathyroidism. METHODS: This retrospective cohort study was conducted on 69 patients divided into three groups, based on the therapeutic strategies (parathyroidectomy, n = 22; cinacalcet, n = 14; calcitriol, n = 33). Changes in systolic blood pressure (SBP) and diastolic blood pressure (DBP) from pre- to post-treatment visits at 1st, 3rd, 6th, and 12th month were analyzed by mixed-effects repeated-measures model. Serum levels of the renin-angiotensin system (RAS) mediators (renin and aldosterone), endothelin, and echocardiography were compared before and after one year of treatment within the three groups. RESULTS: Changes in blood pressure were significantly different among the three groups (SBP: P for group < 0.05; DBP: P for group < .05; both P for group × time interaction < .05). SBP and DBP showed a significant downward trend in the surgery group (P for change in SBP < .05, P for change in DBP < .001, adjusted mean change of SBP = -12.16 (-19.70 to -4.62) mmHg and of DBP = -6.82 (-10.58 to -3.06) mmHg in the surgery group on the 12th month). Diastolic BP showed a significant upward trend in the cinacalcet group (P for change in DBP < .05, adjusted mean change of DBP = 6.03 (2.08 to 9.98) mmHg in cinacalcet group in the 12th month). No significant change in BP was observed in the calcitriol group. The levels of serum RAS mediators, endothelin, or cardiac ultrasonography didn't change and almost remained consistent during the treatment course. CONCLUSION: Blood pressure decreased significantly over a year in patients with parathyroidectomy, while DBP increased significantly over time by cinacalcet treatment.  DOI: 10.52547/ijkd.6686.


Assuntos
Hiperparatireoidismo Secundário , Hipertensão , Pressão Sanguínea , Calcitriol , Cinacalcete/farmacologia , Cinacalcete/uso terapêutico , Humanos , Hiperparatireoidismo Secundário/tratamento farmacológico , Hiperparatireoidismo Secundário/etiologia , Hiperparatireoidismo Secundário/cirurgia , Paratireoidectomia , Diálise Renal/efeitos adversos , Estudos Retrospectivos
18.
Langmuir ; 27(7): 3511-26, 2011 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-21370903

RESUMO

We present GCMC simulations of argon adsorption in slit pores of different channel geometry. We show that the isotherm for an ink-bottle pore can be reconstructed as a linear combination of the local isotherms of appropriately chosen independent unit cells. Second, depending on the system parameters and operating conditions, the phenomena of cavitation and pore blocking can occur for a given configuration of the ink-bottle pore by varying the geometrical aspect ratio. Although it has been argued in the literature that the geometrical aspects of the system govern the evaporation mechanism (either cavitation or pore blocking), we here put forward an argument that the local compressibility in different parts of the ink-bottle pore is the deciding factor for evaporation. When the fluid in the small neck is strongly bound, cavitation is the governing process, and molecules in the cavity evaporate to the surrounding bulk gas via a mass transfer mechanism through the pore neck. When the pore neck is sufficiently large, the system of neck and cavity evaporates at the same pressure, which is a consequence of the comparable compressibility between the fluid in the neck and that in the cavity. This suggests that local compressibility is the measure of cohesiveness of the fluid prior to evaporation. One consequence that we derive from the analysis of isotherms of a number of connected pores is that by analyzing the adsorption branch or the desorption branch of an experimental isotherm may not lead to the correct pore sizes and the correct pore volume distribution.

19.
Langmuir ; 27(23): 14290-9, 2011 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-22013949

RESUMO

We present equations to calculate the differential and integral enthalpy changes of adsorption for their use in Monte Carlo simulation. Adsorption of a system of N molecules, subject to an external potential energy, is viewed as one of transferring these molecules from a reference gas phase (state 1) to the adsorption system (state 2) at the same temperature and equilibrium pressure (same chemical potential). The excess amount adsorbed is the difference between N and the hypothetical amount of gas occupying the accessible volume of the system at the same density as the reference gas. The enthalpy change is a state function, which is defined as the difference between the enthalpies of state 2 and state 1, and the isosteric heat is defined as the negative of the derivative of this enthalpy change with respect to the excess amount of adsorption. It is suitable to determine how the system behaves for a differential increment in the excess phase adsorbed under subcritical conditions. For supercritical conditions, use of the integral enthalpy of adsorption per particle is recommended since the isosteric heat becomes infinite at the maximum excess concentration. With these unambiguous definitions we derive equations which are applicable for a general case of adsorption and demonstrate how they can be used in a Monte Carlo simulation. We apply the new equations to argon adsorption at various temperatures on a graphite surface to illustrate the need to use the correct equation to describe isosteric heat of adsorption.


Assuntos
Simulação de Dinâmica Molecular , Termodinâmica , Adsorção , Argônio/química , Grafite/química , Método de Monte Carlo , Propriedades de Superfície
20.
Exp Ther Med ; 21(2): 157, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33456524

RESUMO

Skin and in particular photoaging or premature aging, are caused by a variety of factors, including hormone imbalance and exposure to ultraviolet radiation. The aim of the present study was to explore the roles of Dual oxidase 2 (DUOX2) and related NF-κB signals in skin photoaging. Cell models of photoaging were constructed by irradiating human skin fibroblast lines (HSF2) with ultraviolet B (UVB) of different doses (0, 15, 30 and 60 mj/cm2). The cell counting kit-8 (CCK8) was used to determine cell proliferation. Flow cytometry was used to determine the production of reactive oxygen species (ROS). A biochemical method was to determine the content of hydrogen peroxide, and the quantitative PCR (qPCR) was used to determine the expression of matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), Col-Ⅰ and α-SMA in the cells. Enzyme-linked immunosorbent assay (ELISA) was used to determine the expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Western blot analysis was performed to determine the expression of DUOX2, p65 and p-p65. The results showed that,UVB irradiation dose- and time-dependently inhibited the proliferation of HSF2 cells. Cellular inflammatory response, ROS production and hydrogen peroxide increase was promoted. Col-Ⅰ and α-SMA were downregulated, MMP2 and MMP9 were upregulated, and the phosphorylation of NF-κB p65 was promoted. The above indicators were all reversed by interference with DUOX2. Overexpression of DUOX2 has an effect that is similar to UVB irradiation, but the effects can be significantly weakened by NF-κB inhibitor, NAC. Upregulation of DUOX2 expression plays a crucial role in UVB-induced aging of HSF2 cells. The specific mechanism is related to the promotion of ROS production and cellular inflammatory response and activation of NF-κB signals.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA