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1.
Ann Oncol ; 35(7): 643-655, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38777726

RESUMO

BACKGROUND: POLE and POLD1 proofreading deficiency (POLE/D1pd) define a rare subtype of ultramutated metastatic colorectal cancer (mCRC; over 100 mut/Mb). Disease-specific data about the activity and efficacy of immune checkpoint inhibitors (ICIs) in POLE/D1pd mCRC are lacking and it is unknown whether outcomes may be different from mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) mCRCs treated with ICIs. PATIENTS AND METHODS: In this global study, we collected 27 patients with mCRC harboring POLE/D1 mutations leading to proofreading deficiency and treated with anti-programmed cell death-ligand 1 alone +/- anti-cytotoxic T-lymphocyte antigen-4 agents. We collected clinicopathological and genomic characteristics, response, and survival outcomes after ICIs of POLE/D1pd mCRC and compared them with a cohort of 610 dMMR/MSI-H mCRC patients treated with ICIs. Further genomic analyses were carried out in an independent cohort of 7241 CRCs to define POLE and POLD1pd molecular profiles and mutational signatures. RESULTS: POLE/D1pd was associated with younger age, male sex, fewer RAS/BRAF driver mutations, and predominance of right-sided colon cancers. Patients with POLE/D1pd mCRC showed a significantly higher overall response rate (ORR) compared to dMMR/MSI-H mCRC (89% versus 54%; P = 0.01). After a median follow-up of 24.9 months (interquartile range: 11.3-43.0 months), patients with POLE/D1pd showed a significantly superior progression-free survival (PFS) compared to dMMR/MSI-H mCRC [hazard ratio (HR) = 0.24, 95% confidence interval (CI) 0.08-0.74, P = 0.01] and superior overall survival (OS) (HR = 0.38, 95% CI 0.12-1.18, P = 0.09). In multivariable analyses including the type of DNA repair defect, POLE/D1pd was associated with significantly improved PFS (HR = 0.17, 95% CI 0.04-0.69, P = 0.013) and OS (HR = 0.24, 95% CI 0.06-0.98, P = 0.047). Molecular profiling showed that POLE/D1pd tumors have higher tumor mutational burden (TMB). Responses were observed in both subtypes and were associated with the intensity of POLE/D1pd signature. CONCLUSIONS: Patients with POLE/D1pd mCRC showed more favorable outcomes compared to dMMR/MSI-H mCRC to treatment with ICIs in terms of tumor response and survival.


Assuntos
Neoplasias Colorretais , DNA Polimerase III , DNA Polimerase II , Inibidores de Checkpoint Imunológico , Mutação , Proteínas de Ligação a Poli-ADP-Ribose , Humanos , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Masculino , Feminino , Inibidores de Checkpoint Imunológico/uso terapêutico , Pessoa de Meia-Idade , Idoso , DNA Polimerase II/genética , Proteínas de Ligação a Poli-ADP-Ribose/genética , DNA Polimerase III/genética , Adulto , Instabilidade de Microssatélites , Idoso de 80 Anos ou mais , Reparo de Erro de Pareamento de DNA
2.
Encephale ; 49(3): 211-218, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35331466

RESUMO

OBJECTIVES: Behavior problems are one of the most common reasons for seeking mental health services in pediatric populations. The objectives are to evaluate the effects of the EQUIPE program (Étude Québécoise d'Intervention pour les Parents d'Enfants avec des problèmes de comportement) and to analyze the impact of the severity of behavior problems and of parental characteristics. METHODS: This program was translated from the Community Parent Education Program. The effects of EQUIPE, as compared to a control group, were evaluated by using Child Behavior Checklist and Parent Stress Index questionnaires before (T0) and after the intervention program (T1), and at 6 (T2) and 12months (T3) follow-up visits. RESULTS: In total, 533 participants were enrolled in intervention (n=465) (with "severe" or "mild" subgroups according to CBCL-T score) and a control group (n=68). In the two groups, the results showed a statistically significant decrease in Child Behavior Checklist and Parent Stress Index total scores at T1, T2 and T3, with the exception of Child Behavior Checklist total scores in the control group at T2. In the intervention group Child Behavior Checklist total scores were significantly higher in the "severe"; which was not the case for Parent Stress Index total scores at T2 and T3. DISCUSSION: Socioeconomic characteristics, family details, parental medical history and the age of the children appeared to influence changes in Child Behavior Checklist and Parent Stress Index total scores. CONCLUSION: The EQUIPE program is an effective intervention for reducing behavior problems and parents' stress in a French-Canadian population.


Assuntos
Serviços de Saúde Mental , Pais , Humanos , Criança , Canadá , Pais/psicologia , Relações Mãe-Filho , Comportamento Infantil/psicologia
3.
Prog Urol ; 32(16): 1455-1461, 2022 Dec.
Artigo em Francês | MEDLINE | ID: mdl-36088200

RESUMO

OBJECTIVES: To assess the morbidity specific of extended pelvic lymphadenectomy during robot-assisted laparoscopic radical prostatectomy in a 8 year retrospective study. MATERIAL: We carried out a single-center, single-surgeon retrospective study on 342 consecutive patients who underwent a robot-assisted laparoscopic radical prostatectomy and extended pelvic lymphadenectomy, from July 2010 to March 2018. Postoperative complications were recorded up to 3 months after the operation. RESULTS: Thirty (8.8%) patients had at least one complication related to lymphadenectomy including 1 vascular injury (0.3%), 7 injuries of the obturator nerve (2%), 5 venous thromboembolic complications (1.5%) including 4 pulmonary embolisms, 10 symptomatic lymphoceles (2.9%) and 8 lymphoedemas (2.3%). Of these complications, 13 were classified Clavien 1 (43.3%), 8 Clavien 2 (26.7%), 7 Clavien 3a (23.3%) and 2 Clavien 3b (6.7%). In univariate analysis a high age (P=0.04), high BMI (P<0.01) and pT stage (P=0.02) were significantly associated with complication whereas in multivariate analysis, only age (P=0.02) and BMI (P<0.01) lived were. In univariate analysis high BMI (P=0.04) and lymph node involvement (P=0.04) were associated with lymphatic complication. We did not find any other specific risk factor for the other complications. CONCLUSION: With 8.8% of overall complications related to lymphadenectomy and 5% of complication classified Clavien grade 2 or higher, extended pelvic lymphadenectomy was not very morbid. Age and BMI were risk factors for a overall complication. BMI and lymph node involvement were risk factors for lymphatic complications. LEVEL OF PROOF: 4.


Assuntos
Laparoscopia , Linfocele , Neoplasias da Próstata , Robótica , Masculino , Humanos , Próstata/patologia , Estudos Retrospectivos , Prostatectomia/efeitos adversos , Excisão de Linfonodo/efeitos adversos , Neoplasias da Próstata/patologia , Linfocele/epidemiologia , Linfocele/etiologia , Laparoscopia/efeitos adversos , Pelve/patologia , Morbidade
5.
Biochem Biophys Res Commun ; 569: 23-28, 2021 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-34216994

RESUMO

Intravenous injections of human hematopoietic stem cells (hHSCs) is routinely used in clinic and for modeling hematopoiesis in mice. However, unspecific dilution in vascular system and non-hematopoietic organs challenges engraftment efficiency. Although spleen is capable of extra medullar hematopoiesis, its ability to support human HSC transplantation has never been evaluated. We demonstrate that intra-splenic injection results in high and sustained engraftment of hHSCs into immune-deficient mice, with higher chimerisms than with intravenous or intra-femoral injections. Our results support that spleen microenvironment provides a niche for HSCs amplification and offers a new route for efficient HSC transplantation.


Assuntos
Sobrevivência de Enxerto/fisiologia , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/citologia , Baço/citologia , Animais , Antígenos CD34/metabolismo , Feminino , Citometria de Fluxo/métodos , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Injeções , Luciferases/genética , Luciferases/metabolismo , Medições Luminescentes/métodos , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Baço/metabolismo , Quimeras de Transplante , Transplante Heterólogo
7.
Rev Sci Instrum ; 91(12): 123102, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33379964

RESUMO

This work describes the correction method applied to the dataset acquired at the asteroid (4) Vesta by the visible channel of the visible and infrared mapping spectrometer. The rising detector temperature during data acquisitions in the visible wavelengths leads to a spectral slope increase over the whole spectral range. This limits the accuracy of the studies of the Vesta surface in this wavelength range. Here, we detail an empirical method to correct for the visible detector temperature dependency while taking into account the specificity of the Vesta dataset.

8.
Eur Phys J E Soft Matter ; 42(7): 86, 2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31289962

RESUMO

This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented. Finally, multi-component mixtures studied in the SCCO project are detailed.

9.
Br J Surg ; 106(9): 1237-1247, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31183866

RESUMO

BACKGROUND: BRAF mutation is associated with a poor prognosis in patients with metastatic colorectal cancer. For patients with resectable colorectal liver metastases (CRLMs), the prognostic impact of BRAF mutation is unknown and the benefit of surgery debated. This nationwide intergroup (ACHBT, FRENCH, AGEO) study aimed to evaluate the oncological outcome of patients undergoing liver resection for BRAF-mutated CRLMs. METHODS: The study included patients who underwent resection for BRAF-mutated CRLMs in 24 centres between 2012 and 2016. A case-matched comparison was made with 183 patients who underwent resection of CRLMs with wild-type BRAF during the same interval. RESULTS: Sixty-six patients who underwent resection for BRAF-mutated CRLMs in 24 centres were compared with 183 patients with wild-type BRAF. The 1- and 3-year disease-free survival (DFS) rates were 46 and 19 per cent for the BRAF-mutated group, and 55·4 and 27·8 per cent for the group with wild-type BRAF (P = 0·430). In multivariable analysis, BRAF mutation was not associated with worse DFS (hazard ratio 1·16, 95 per cent c.i. 0·72 to 1·85; P = 0·547). The 1- and 3-year overall survival rates after surgery were 94 and 54 per cent respectively among patients with BRAF mutation, and 95·8 and 82·9 per cent in those with wild-type BRAF (P = 0·004). Median survival after disease progression was 23·0 (95 per cent c.i. 11·0 to 35·0) months among patients with mutated BRAF and 44·3 (35·9 to 52·6) months in those with wild-type BRAF (P = 0·050). Multisite disease progression was more common in the BRAF-mutated group (48 versus 29·8 per cent; P = 0·034). CONCLUSION: These results support surgical treatment for resectable BRAF-mutated CRLM, as BRAF mutation by itself does not increase the risk of relapse after resection. BRAF mutation is associated with worse survival in patients whose disease relapses after resection of CRLM, as for non-metastatic colorectal cancer.


Assuntos
Neoplasias Colorretais/genética , Neoplasias Hepáticas/secundário , Recidiva Local de Neoplasia/genética , Proteínas Proto-Oncogênicas B-raf/genética , Idoso , Estudos de Casos e Controles , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Intervalo Livre de Doença , Feminino , Hepatectomia , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/cirurgia , Masculino , Pessoa de Meia-Idade , Mutação/genética , Análise de Sobrevida
10.
Rev Sci Instrum ; 90(12): 123110, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31893819

RESUMO

Data acquired at Ceres by the visible channel of the Visible and InfraRed mapping spectrometer (VIR) on board the NASA Dawn spacecraft are affected by the temperatures of both the visible (VIS) and the infrared (IR) sensors, which are, respectively, a charged coupled device and a HgCdTe array. The variations of the visible channel temperatures measured during the sessions of acquisitions are correlated with the variations in the spectral slope and shape for all the mission phases. The IR channel temperature is more stable during the acquisitions; nonetheless, it is characterized by a bimodal distribution whether the cryocooler (and, therefore, the IR channel) is used or not during the visible channel operations. When the infrared channel temperature is high (175 K, i.e., not in use and with the cryocooler off), an additional negative slope and a distortion are observed in the spectra of the visible channel. We developed an empirical correction based on a reference spectrum for the whole dataset; it is designed to correct the two issues related to the sensor temperatures that we have identified. The reference spectrum is calculated to be representative of the global Ceres' surface. It is also made of the data acquired when the visible and infrared channel temperatures are equal to the ones measured during an observation of the Arcturus star by VIR, which is consistent with several ground-based observations. The developed correction allows reliable analysis and mapping to be performed by minimizing the artifacts induced by fluctuations of the VIS temperature. Thanks to this correction, a direct comparison between different mission phases during which the VIR experienced different visible and infrared channel temperatures is now possible.

11.
Clin Transl Radiat Oncol ; 10: 13-22, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29928701

RESUMO

An estimated 990,000 new cases of gastric cancer are diagnosed worldwide each year. Surgical excision, the only chance for prolonged survival, is feasible in about 20% of cases. Even after surgery, the median survival is limited to 12 to 20 months due to the frequency of locoregional and/or metastatic recurrences. This led to clinical trials associating surgery with neoadjuvant or adjuvant treatments to improve tumor control and patient survival. The most studied modalities are perioperative chemotherapy and adjuvant chemoradiotherapy. To date, evidence has shown a survival benefit for postoperative chemoradiotherapy and for perioperative chemotherapy. Phase III trials are ongoing to compare these two modalities. The aim of this review is to synthesize current knowledge about adjuvant chemoradiotherapy in the management of gastric adenocarcinoma, and to consider its prospects by integrating modern radiotherapy techniques.

12.
J Chem Phys ; 148(18): 184702, 2018 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-29764126

RESUMO

An artificial oil-in-water emulsion analogous to those found in bioresources or food matrices is simulated and studied experimentally. It is composed of one of the major natural free fatty acids (the oleic acid, OA) and the corresponding triacylglyceride (trioleic glyceride, or triolein, GTO). Because of the large time and length scales involved, the molecular simulations are done with the Martini force field, a coarse-grained model. This allowed us to study the water-OA-GTO system at different compositions with more than 20 000 molecules and up to 2 µs. Interfacial tension was measured using the pendant drop method and compared with molecular simulation results. We observe very good agreement at high OA concentrations and deviations up to 15% at low OA concentrations. The water solubility in the lipid phase is in fair agreement with experiments, between 0.03 and 0.32 mol/l, rising with the OA content. The area occupied by OA and GTO at the interface between water and the pure product fitted with experimental data (AOA = 36.6 Å2 and AGTO = 152.1 Å2). The consistency between simulation and experimental results allowed a structural analysis of the interface. A bilayer structure of the lipids at the water/oil interface is proposed, containing preferentially oleic acid but also triolein. Through all these results, the usefulness of coarse-grained simulation for the description of water-oil interfacial organization is demonstrated. This method will be used later to bring local information on the organization of target compounds, necessary in biomass fractionation processes or food additive formulations, for example.

13.
Rev Med Interne ; 39(6): 393-399, 2018 Jun.
Artigo em Francês | MEDLINE | ID: mdl-29716754

RESUMO

BACKGROUND: Medication reconciliation (MR) is a systematic and comprehensive review of all medication a patient is taking. In this study, a discharge medication sheet (DMS) is given to patients upon discharge: it contains discharge prescription and any changes made to admission prescription with justifications. The aim of this study is to explore general practitioners' (GP) perceptions of this DMS in order to suggest improvements. METHODS: In this prospective observational study, individual semi-directed interviews were conducted with GPs who received a DMS following the hospitalization of one of their patients. Answers were grouped by topic and subjected to descriptive analysis. RESULTS: Between October 2015 and July 2016, 33 DMS were completed. Among the 33 GPs, 16 had seen their patients with their DMS and agreed to be interviewed. The DMS was very appreciated and improved care pathway. However, this study highlights transmission difficulties for this sheet, attributed in particular to a lack of information of practitioners and patients and to the paper format, which appears to be inadequate. The main suggested improvement is real-time transmission of the DMS via email. CONCLUSION: Practitioners' opinion is in favor of the use of a DMS. Certain specific points need to be improved, such as better information of practitioners and patients, and transmission of the DMS via a secure email system.


Assuntos
Atitude do Pessoal de Saúde , Continuidade da Assistência ao Paciente/organização & administração , Clínicos Gerais , Reconciliação de Medicamentos/métodos , Alta do Paciente , Adulto , Idoso , Continuidade da Assistência ao Paciente/normas , Feminino , Clínicos Gerais/psicologia , Clínicos Gerais/estatística & dados numéricos , Humanos , Masculino , Reconciliação de Medicamentos/organização & administração , Reconciliação de Medicamentos/estatística & dados numéricos , Pessoa de Meia-Idade , Alta do Paciente/normas , Alta do Paciente/estatística & dados numéricos , Percepção , Padrões de Prática Médica/estatística & dados numéricos
14.
Oncogene ; 35(43): 5619-5628, 2016 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-27157616

RESUMO

Gastric carcinoma is the third leading cause of cancer-related death worldwide. This cancer, most of the time metastatic, is essentially treated by surgery associated with conventional chemotherapy, and has a poor prognosis. The existence of cancer stem cells (CSC) expressing CD44 and a high aldehyde dehydrogenase (ALDH) activity has recently been demonstrated in gastric carcinoma and has opened new perspectives to develop targeted therapy. In this study, we evaluated the effects of all-trans-retinoic acid (ATRA) on CSCs in human gastric carcinoma. ATRA effects were evaluated on the proliferation and tumorigenic properties of gastric carcinoma cells from patient-derived tumors and cell lines in conventional 2D cultures, in 3D culture systems (tumorsphere assay) and in mouse xenograft models. ATRA inhibited both tumorspheres initiation and growth in vitro, which was associated with a cell-cycle arrest through the upregulation of cyclin-dependent kinase (CDK) inhibitors and the downregulation of cell-cycle progression activators. More importantly, ATRA downregulated the expression of the CSC markers CD44 and ALDH as well as stemness genes such as Klf4 and Sox2 and induced differentiation of tumorspheres. Finally, 2 weeks of daily ATRA treatment were sufficient to inhibit gastric tumor progression in vivo, which was associated with a decrease in CD44, ALDH1, Ki67 and PCNA expression in the remaining tumor cells. Administration of ATRA appears to be a potent strategy to efficiently inhibit tumor growth and more importantly to target gastric CSCs in both intestinal and diffuse types of gastric carcinoma.


Assuntos
Antineoplásicos/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/metabolismo , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patologia , Tretinoína/farmacologia , Aldeído Desidrogenase/metabolismo , Animais , Biomarcadores , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Humanos , Receptores de Hialuronatos/metabolismo , Imunofenotipagem , Fator 4 Semelhante a Kruppel , Camundongos , Esferoides Celulares , Neoplasias Gástricas/tratamento farmacológico , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
18.
Br J Cancer ; 113(9): 1313-22, 2015 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-26528707

RESUMO

BACKGROUND: Bone metastases (BMs) are associated with poor outcome in metastatic clear-cell renal carcinoma (m-ccRCC) treated with anti-vascular endothelial growth factor tyrosine kinase inhibitors (anti-VEGFR-TKIs). We aimed to investigate whether expression in the primary tumour of genes involved in the development of BM is associated with outcome in m-ccRCC patients treated with anti-VEGFR-TKIs. METHODS: Metastatic clear-cell renal cell carcinoma patients with available fresh-frozen tumour and treated with anti-VEGFR-TKIs. Quantitative real-time PCR (qRT-PCR) for receptor activator of NF-kB (RANK), RANK-ligand (RANKL), osteoprotegerin (OPG), the proto-oncogene SRC and DKK1 (Dickkopf WNT signalling pathway inhibitor-1). Time-to-event analysis by Kaplan-Meier estimates and Cox regression. RESULTS: We included 129 m-ccRCC patients treated between 2005 and 2013. An elevated RANK/OPG ratio was associated with shorter median time to metastasis (HR 0.50 (95% CI 0.29-0.87); P=0.014), shorter time to BM (HR 0.54 (95% CI 0.31-0.97); P=0.037), shorter median overall survival (mOS) since initial diagnosis (HR 2.27 (95% CI 1.44-3.60); P=0.0001), shorter median progression-free survival (HR 0.44 (95% CI 0.28-0.71); P=0.001) and mOS (HR 0.31 (95% CI 0.19-0.52); P<0.0001) on first-line anti-VEGFR-TKIs in the metastatic setting. Higher RANK expression was associated with shorter mOS on first-line anti-VEGFR-TKIs (HR 0.46 (95% CI 0.29-0.73); P=0.001). CONCLUSIONS: RANK/OPG ratio of expression in primary ccRCC is associated with BM and prognosis in patients treated with anti-VEGFR-TKIs. Prospective validation is warranted.


Assuntos
Neoplasias Ósseas/patologia , Carcinoma de Células Renais/genética , Neoplasias Renais/genética , Osteoprotegerina/genética , Proteínas Tirosina Quinases/antagonistas & inibidores , Receptor Ativador de Fator Nuclear kappa-B/genética , Receptores de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Neoplasias Ósseas/genética , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/patologia , Intervalo Livre de Doença , Feminino , Genes src/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/patologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Inibidores de Proteínas Quinases/uso terapêutico , Proto-Oncogene Mas , Ligante RANK/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
19.
Chem Commun (Camb) ; 51(57): 11482-4, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-26091539

RESUMO

Recombinant proteins bearing a tag are crucial tools for assessing protein location or function. Small tags such as Cys4 tag (tetracysteine; Cys-Cys-X-X-Cys-Cys) are less likely disrupt protein function in the living cell than green fluorescent protein. Herein we report the first example of the design and synthesis of a dual fluorescence and hyperpolarized (129)Xe NMR-based sensor of Cys4-tagged proteins. This sensor becomes fluorescent when bound to such Cys4-tagged peptides, and the (129)Xe NMR spectrum exhibits a specific signal, characteristic of the biosensor-peptide association.


Assuntos
Cisteína/análise , Fluoresceínas/química , Corantes Fluorescentes/química , Compostos Organometálicos/química , Peptídeos/análise , Compostos Policíclicos/química , Sequência de Aminoácidos , Técnicas Biossensoriais , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular , Proteínas Recombinantes/análise , Espectrometria de Fluorescência , Isótopos de Xenônio/química
20.
J Phys Chem A ; 119(1): 140-51, 2015 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-25479370

RESUMO

A classical all-atoms force field for molecular simulations of hydrofluorocarbons (HFCs) has been developed. Lennard-Jones force centers plus point charges are used to represent dispersion-repulsion and electrostatic interactions. Parametrization of this force field has been performed iteratively using three target properties of pentafluorobutane: the quantum energy of an isolated molecule, the dielectric constant in the liquid phase, and the compressed liquid density. The accuracy and transferability of this new force field has been demonstrated through the simulation of different thermophysical properties of several fluorinated compounds, showing significant improvements compared to existing models. This new force field has been applied to study solubilities of several gases in poly(vinylidene fluoride) (PVDF) above the melting temperature of this polymer. The solubility of CH4, CO2, H2S, H2, N2, O2, and H2O at infinite dilution has been computed using test particle insertions in the course of a NpT hybrid Monte Carlo simulation. For CH4, CO2, and their mixtures, some calculations beyond the Henry regime have also been performed using hybrid Monte Carlo simulations in the osmotic ensemble, allowing both swelling and solubility determination. An ideal mixing behavior is observed, with identical solubility coefficients in the mixtures and in pure gas systems.

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