Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 83
Filtrar
1.
J Phys Chem B ; 128(25): 6134-6150, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38874477

RESUMO

Due to their many attractive physicochemical properties, ionic liquids (ILs) have received extensive attention with numerous applications proposed in various fields of science and technology. Despite this, the molecular origins of many of their properties, such as the moisture absorption capability, are still not well understood. For insight into this, we systematically synthesized 24 types of ILs by the combination of the dimethyl phosphate anion with various types of alkyl group-substituted cyclic cations─imidazolium, pyrazolium, 1,2,3-triazolium, and 1,2,4-triazolium cations─and performed a detailed analysis of the dehumidification properties of these ILs and their aqueous solutions. It was found that these IL systems have a high dehumidification capability (DC). Among the monocationic ILs, the best performance was obtained with 1-cyclohexylmethyl-4-methyl-1,2,4-triazolium dimethyl phosphate, whose DC (per mol) value is 14 times higher than that of popular solid desiccants like CaCl2 and silica gel. Dicationic ILs, such as 1,1'-(propane-1,3-diyl)bis(4-methyl-1,2,4-triazolium) bis(dimethyl phosphate), showed an even better moisture absorption, with a DC (per mol) value about 20 times higher than that of CaCl2. Small- and wide-angle X-ray scattering measurements of eight types of 1,2,4-triazolium dimethyl phosphate ILs were performed and revealed that the majority of these ILs form nanostructures. Such nanostructures, which vary with the identity of the IL and the water content, fall into three main categories: bicontinuous microemulsions, hexagonal cylinders, and micelle-like structures. Water in the solutions exists primarily in polar regions in the nanostructures; these spaces function as water pockets at relatively low water concentrations. Since the structure and stability of the aggregated forms of the ILs are mainly governed by the interactions of nonpolar groups, the alkyl side chains of the cations play an important role in the DC and temperature-dependent equilibrium water vapor pressure of the IL solutions. Our experimental findings and molecular dynamics simulation results shed light on the moisture absorption mechanism of the IL aqueous solutions from a molecular perspective.

2.
J Phys Chem B ; 127(42): 9191-9203, 2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37820068

RESUMO

Infrared (IR) spectra of solutions of the lithium salt LiBF4 in diglyme, CH3O(CH2CH2O)2CH3, are studied via IR spectroscopy and ab initio molecular dynamics (AIMD) simulations. Experiments show that the major effects of LiBF4, compared to neat diglyme, are the appearance of a new broad band in the 250-500 cm-1 frequency region and a broadening and intensity enhancement of the diglyme band in the 900-1150 cm-1 region accompanied by a red-shift. Computational analysis indicates that hindered translational motions of Li+ in its solvation cage are mainly responsible for the new far-IR band, while the changes in the mid-IR are due to Li+-coordination-dependent B-F stretching vibrations of BF4- anions coupled with diglyme vibrations. Molecular motions in these and lower frequency regions are generally correlated, revealing the collective nature of the vibrational dynamics, which involve multiple ions/molecules. Herein, a detailed analysis of these features via AIMD simulations of the spectrum and its components, combined with analysis of the generalized normal modes of the solution components, is presented. Other minor spectral changes as well as diglyme conformational changes induced by the lithium salt are also discussed.

3.
Chem Rec ; 23(8): e202300075, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37166396

RESUMO

A brief account is given of highlights of our computational efforts - often in collaboration with experimental groups - to understand spectroscopic and chemical properties of ionic liquids (ILs). Molecular dynamics, including their inhomogeneous character, responsible for key spectral features observed in dielectric absorption, infra-red (IR) and fluorescence correlation spectroscopy (FCS) measurements are elucidated. Mechanisms of chemical processes involving imidazolium-based ILs are illustrated for CO2 capture and related reactions, transesterification of cellulose, and Au nanocluster-catalyzed Suzuki cross-coupling reaction with attention paid to differing roles of IL ions. A comparison with experiments is also made.

4.
Front Psychol ; 13: 973493, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36467228

RESUMO

The ongoing COVID-19 pandemic has increased the psychological burden on employees in hotels, which is not conducive to the development of the hospitality industry. Based on a survey of 379 hotel interns from higher vocational colleges in China, this study empirically analyzed the status quo of job burnout in future hotel employees and its influencing factors. The results showed that interns' job burnout and reduced personal accomplishment were at a medium level. Secondly, according to the transaction model, this study classified the antecedents of job burnout into two categories: personal factors and contextual factors. The results showed that personal factors such as attitude and self-efficacy, and contextual factors such as perceived co-worker support and job satisfaction all had a negative effect on job burnout. However, the influence of ability and perceived supervisor support on job burnout was not significant. This study also investigated the influencing factors of each sub-dimension of job burnout. Self-efficacy, attitude and job satisfaction all had a negative influence on the three sub-dimensions. Ability and perceived co-worker support only had a negative impact on reduced personal accomplishment. There was no statistical correlation between perceived supervisor support and the three sub-dimensions. The results of this study will lay a theoretical foundation so that higher vocational colleges can better organize and implement internships, and hotels can recruit energetic future employees.

5.
J Phys Chem B ; 126(46): 9643-9662, 2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36326052

RESUMO

Infrared (IR) spectra of solutions of the lithium salt LiBF4 in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4) and in the organic solvent propylene carbonate (PC) are studied via infrared spectroscopy and ab initio molecular dynamics (AIMD) simulations. The measurements show that the major effects of LiBF4 in both solutions, compared to their neat counterparts, are the appearance of a new broad band in the 300-450 cm-1 frequency region and a broadening of the IR structure in the 900-1200 cm-1 region with the development of a new peak at 980 cm-1. Computational analysis indicates that hindered translational motions of Li+ in its solvation cage are mainly responsible for the former, while the latter is due to Li+-induced structural changes and accompanying vibrational frequency shifts of constituent ions and molecules of the solutions. In addition, molecular motions in these and lower-frequency regions are generally correlated, disclosing the collective nature of the vibrational dynamics, which involve multiple ions/molecules. Herein, a detailed analysis of these features via AIMD simulations of the spectrum and its components arising from auto- and cross-correlations of motions of constituent molecular species, combined with generalized normal modes of the solutions and normal modes of small Li+-containing clusters, is presented. Other minor spectral changes caused by the lithium salt as well as the interaction-induced effect on IR spectra are also discussed.

6.
Cell Rep ; 40(3): 111099, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35858562

RESUMO

Many therapeutic antibodies deplete target cells and elicit immunotherapy by engaging activating Fc gamma receptors (FcγRs) on host effector cells. These antibodies are negatively regulated by the inhibitory FcγRIIB (CD32B). Dogma suggests inhibition is mediated through the FcγRIIB immunoreceptor tyrosine-based inhibition motif (ITIM), negatively regulating immunoreceptor tyrosine-based activation motif (ITAM)-mediated signaling from activating FcγR. To assess this, we generated experimental models expressing human (h)FcγRIIB on targets or effectors, lacking or retaining ITIM signaling capacity. We demonstrate that signaling through the hFcγRIIB ITIM is dispensable for impairing monoclonal antibody (mAb)-mediated depletion of normal and malignant murine target cells through three therapeutically relevant surface receptors (CD20, CD25, and OX40) affecting immunotherapy. We demonstrate that hFcγRIIB competition with activating FcγRs for antibody Fc, rather than ITIM signaling, is sufficient to impair activating FcγR engagement, inhibiting effector function and immunotherapy.


Assuntos
Anticorpos Monoclonais , Receptores de IgG/imunologia , Animais , Humanos , Imunoterapia , Camundongos , Receptores de IgG/metabolismo , Transdução de Sinais
7.
J Cell Physiol ; 237(8): 3381-3393, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35696529

RESUMO

Cytoplasmic serine/threonine Pim kinases have emerged as important modulators of immune regulation and oncology. However, their regulatory roles in bone remodeling remain obscure. Here, we aimed to determine the roles of Pim kinases in periodontal disease (PD), focusing on the regulation of osteoclastogenesis and bone resorptive activity. We investigated Pim kinases expression in PD by analyzing data from the online Gene Expression Omnibus database and using ligature-induced periodontitis mouse model. The expression of Pim kinases during receptor activator of nuclear factor kB ligand (RANKL)-induced osteoclastogenesis was assessed in mouse bone marrow-derived macrophages (BMMs) using reverse transcription polymerase chain reaction. Osteoclast differentiation and bone resorption activity were respectively verified by tartrate-resistant acid phosphatase staining and dentin disc-based bone resorption assays. We silenced and overexpressed Pim-2 using small interfering RNA (siRNA) and retroviral vector, respectively, to investigate the molecular mechanisms underlying Pim-2 regulation in RANKL-induced osteoclastogenesis and bone resorption activity. Upregulated expression of Pim-2 was observed in both patients with PD and periodontitis-affected mouse gingival tissues. siRNA-mediated silencing of Pim-2 in BMMs diminished RANKL-induced resorptive activity without affecting osteoclastogenesis. Moreover, RANKL-triggered stimulation of a3 isoform, which is a subunit of vacuolar-type ATPase, was selectively attenuated in BMMs on silencing Pim-2. The overexpression of Pim-2 with a retroviral vector stimulated the a3 subunit, thus inducing bone resorption activity. Taken together, these results suggest that Pim-2 acts as a major modulator of osteoclastic activity by regulating a3 isoform expression in PD.


Assuntos
Reabsorção Óssea , Doenças Periodontais , Proteínas Serina-Treonina Quinases , Proteínas Proto-Oncogênicas , ATPases Vacuolares Próton-Translocadoras , Animais , Reabsorção Óssea/genética , Reabsorção Óssea/metabolismo , Diferenciação Celular , Inativação Gênica , Camundongos , Osteoclastos/metabolismo , Doenças Periodontais/genética , Doenças Periodontais/metabolismo , Periodontite/genética , Periodontite/metabolismo , Isoformas de Proteínas/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Ligante RANK/metabolismo , RNA Interferente Pequeno/genética , ATPases Vacuolares Próton-Translocadoras/metabolismo
8.
Biochemistry ; 61(7): 563-574, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35315646

RESUMO

The ammonia-oxidizing bacterium Nitrosomonas europaea expresses two cytochromes in the P460 superfamily that are predicted to be structurally similar. In one, cytochrome (cyt) P460, the substrate hydroxylamine (NH2OH) is converted to nitric oxide (NO) and nitrous oxide (N2O) requiring a unique heme-lysyl cross-link in the catalytic cofactor. In the second, cyt c'ß-Met, the cross-link is absent, and the cytochrome instead binds H2O2 forming a ferryl species similar to compound II of peroxidases. Here, we report the 1.80 Å crystal structure of cyt c'ß-Met─a well-expressed protein in N. europaea with a lysine to a methionine replacement at the cross-linking position. The structure of cyt c'ß-Met is characterized by a large ß-sheet typical of P460 members; however, several localized structural differences render cyt c'ß-Met distinct. This includes a large lasso-like loop at the "top" of the cytochrome that is not observed in other structurally characterized members. Active site variation is also observed, especially in comparison to its closest homologue cyt c'ß from the methane-oxidizing Methylococcus capsulatus Bath, which also lacks the cross-link. The phenylalanine "cap" which is presumed to control small ligand access to the distal heme iron is replaced with an arginine, reminiscent of the strictly conserved distal arginine in peroxidases and to the NH2OH-oxidizing cytochromes P460. A critical proton-transferring glutamate residue required for NH2OH oxidation is nevertheless missing in the active site. This in part explains the inability of cyt c'ß-Met to oxidize NH2OH. Our structure also rationalizes the absence of a methionyl cross-link, although the side chain's spatial position in the structure does not eliminate the possibility that it could form under certain conditions.


Assuntos
Amônia , Nitrosomonas europaea , Amônia/metabolismo , Citocromos/química , Peróxido de Hidrogênio , Oxirredução
9.
J Am Soc Mass Spectrom ; 33(3): 521-529, 2022 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-35147432

RESUMO

Cryodetection mass spectrometry (MS) was used to study the Au10(TBBT)10 (TBBT = 4-tert-butylbenzenethiolate) catenane nanocluster. The matrix-assisted laser desorption ionization (MALDI) process generates distinct fragments that can be arranged into two distinct regimes: (i) in-source fragmentation, which occurs rapidly in a relatively short (<170 ns) time frame, and (ii) metastable fragmentation, which occurs postacceleration during a time-of-flight (TOF) mass analysis over a longer time frame (>170 ns-250 µs). Using MALDI-TOF MS with superconducting tunnel junction (STJ) cryodetection, distinct metastable nanocluster fragments were resolved at lower energies deposited into the detector. The results also demonstrated that STJ cryodetection MS can be used to acquire multiple (>10), simultaneous tandem mass spectra in a single experiment. Simulated fragmentation of the Au10 nanocluster using ab initio molecular dynamics (AIMD) revealed the different fragmentation processes and confirmed the MS results. Using both the empirical MS data and AIMD calculations, fragmentation pathways are proposed for Au10(TBBT)10, which terminate with two small, stable ringed species.

10.
Eur J Cancer ; 140: 19-27, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33039810

RESUMO

BACKGROUND: Hand-foot skin reaction (HFSR) is the most common adverse event during sorafenib treatment in patients with hepatocellular carcinoma (HCC). In the present study, we aimed to investigate the role of urea cream in the prevention of HFSR or amelioration of HFSR severity. PATIENTS AND METHODS: Patients with HCC were treated with either placebo cream or urea cream for 12 weeks concomitantly with sorafenib treatment. HFSR development, the Hand-Foot Skin Reaction and Quality of Life (HF-QoL) questionnaire score, and adverse events were assessed at 2, 4, 8 and 12 weeks. RESULTS: Of the 288 patients, 247 patients, with 117 patients in the placebo control group and 130 patients in the urea cream group, were analysed. The urea cream group showed a trend towards a lower cumulative incidence of any-grade HFSR (log-rank, P = 0.247) and severe HFSR of grade II or higher (log-rank, P = 0.394) without statistical significance. In the incidence by time point, the incidence of severe HFSR of grade II or higher was significantly lower in the urea cream group than in the placebo control group at 2 weeks (13.8% versus 23.9%, P = 0.042). The urea cream group showed a significantly better HF-QoL questionnaire score than the placebo control group (11.8 versus 19.7, P = 0.014) at 12 weeks. CONCLUSIONS: Treatment with urea cream showed a lower incidence of severe sorafenib-induced HFSR at 2 weeks and reduced the tendency of HFSR development in HCC patients. Therefore, treatment with urea cream may be considered for prophylaxis or improvement of HFSR grade in HCC patients treated with sorafenib. TRIAL REGISTRATION: ClinicalTrials.gov (NCT03212625).


Assuntos
Síndrome Mão-Pé/tratamento farmacológico , Síndrome Mão-Pé/etiologia , Creme para a Pele/uso terapêutico , Dermatopatias/induzido quimicamente , Dermatopatias/tratamento farmacológico , Sorafenibe/efeitos adversos , Ureia/uso terapêutico , Idoso , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Método Duplo-Cego , Feminino , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Pele/efeitos dos fármacos , Sorafenibe/uso terapêutico
11.
Biochemistry ; 59(5): 704-716, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31887031

RESUMO

A defining characteristic of bacterial cytochromes (cyt's) in the P460 family is an unusual cross-link connecting the heme porphyrin to the side chain of a lysyl residue in the protein backbone. Here, via proteomics of the periplasmic fraction of the ammonia-oxidizing bacterium (AOB) Nitrosomonas europaea, we report the identification of a variant member of the P460 family that contains a methionyl residue in place of the cross-linking lysine. We formally designate this protein cytochrome "c'ß-Met" to distinguish it from other members bearing different residues at this position (e.g., cyt c'ß-Phe from the methane-oxidizing Methylococcus capsulatus Bath). As isolated, the monoheme cyt c'ß-Met is high-spin (S = 5/2). Optical spectroscopy suggests that a cross-link is absent. Hydroxylamine, the substrate for the cross-linked cyt P460 from N. europaea, did not appreciably alter the optical spectrum of cyt c'ß with up to 1000-fold excess at pH 7.5. Cyt c'ß-Met did however bind 1 equiv of H2O2, and with a slight excess, Mössbauer spectroscopy indicated the formation of a semistable ferryl (FeIV═O) Compound II-like species. The corresponding electron paramagnetic resonance showed a very low intensity signal indicative of a radical at g = 2.0. Furthermore, cyt c'ß-Met exhibited guaiacol-dependent peroxidase activity (kcat = 20.0 ± 1.2 s-1; KM = 2.6 ± 0.4 mM). Unlike cyt c'ß-Met, cyt P460 showed evidence of heme inactivation in the presence of 2 equiv of H2O2 with no appreciable guaiacol-dependent peroxidase activity. Mutagenesis of the cross-linking lysyl residue to an alanine in cyt P460, however, reversed this lack of activity.


Assuntos
Citocromos c/metabolismo , Heme/metabolismo , Compostos de Ferro/metabolismo , Lisina/metabolismo , Nitrosomonas/química , Peroxidase/metabolismo , Citocromos c/química , Citocromos c/genética , Espectroscopia de Ressonância de Spin Eletrônica , Heme/química , Compostos de Ferro/química , Lisina/química , Modelos Moleculares , Nitrosomonas/citologia , Nitrosomonas/metabolismo , Peroxidase/química , Proteômica , Espectroscopia de Mossbauer
12.
Ann Surg ; 269(1): 108-113, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-28742692

RESUMO

OBJECTIVE: To determine the toxicity and oncologic outcome of neoadjuvant chemoradiotherapy (CRT) followed by curative total mesorectal excision (TME) in the elderly (≥70 yrs) and younger (<70 yrs) rectal cancer patients. BACKGROUND: Sufficient data for elderly rectal cancer patients who received definitive trimodality have not been accumulated yet. PATIENTS AND METHODS: A total of 1232 rectal cancer patients who received neoadjuvant CRT and TME were enrolled in this study. After propensity-score matching, 310 younger patients and 310 elderly patients were matched with 1:1 manner. Treatment response, toxicity, surgical outcome, recurrence, and survival were assessed and compared between the 2 groups of patients. RESULTS: The median age was 58 years for the younger patient group and 74 years for the elderly group. Pathologic complete response rates were not significantly different between the 2 groups (younger and elderly: 17.1% vs 14.8%, P = 0.443). The 5-year recurrence-free survival (younger and elderly: 67.7% vs 65.5%, P = 0.483) and overall survival (younger and elderly: 82.9% vs. 79.5%, P = 0.271) rates were not significantly different between the 2 groups either. Adjuvant chemotherapy after surgery was less frequently delivered to the elderly than that to younger patients (83.9% vs 69.0%). Grade 3 or higher acute hematologic toxicity was observed more frequently in the elderly than that in the younger group (9.0% vs 16.1%, P = 0.008). Late complication rate was higher in the elderly group compared with that in the younger group without statistical significance (2.6% vs 4.5%, P = 0.193). CONCLUSIONS: Although acute hematologic toxicity was observed more frequently in the elderly patients than that in the younger patients, elderly rectal cancer patients with good performance status who received preoperative CRT and TME showed favorable tumor response and recurrence-free survival similar to younger patients.


Assuntos
Adenocarcinoma/terapia , Antineoplásicos/uso terapêutico , Colectomia/métodos , Recidiva Local de Neoplasia/epidemiologia , Cuidados Pré-Operatórios/métodos , Pontuação de Propensão , Neoplasias Retais/terapia , Adenocarcinoma/diagnóstico , Adenocarcinoma/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Quimiorradioterapia Adjuvante , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Morbidade/tendências , Terapia Neoadjuvante , Estadiamento de Neoplasias , Prognóstico , Neoplasias Retais/diagnóstico , Neoplasias Retais/mortalidade , Reto/cirurgia , República da Coreia/epidemiologia , Estudos Retrospectivos , Taxa de Sobrevida/tendências
13.
ACS Appl Mater Interfaces ; 10(47): 40599-40607, 2018 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-30381951

RESUMO

Hybrid catalysts composed of gold-palladium nanoalloys that are sandwiched between layers of graphene oxide (GO) and lamellar TiO2 are synthesized via the deposition-reduction method. The resulting AuPd catalysts with different compositions of metal and support are fully characterized by a series of techniques, including X-ray diffraction, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry. The catalysts are also optimized against Au, Pd, GO, and TiO2 contents and employed in the direct synthesis of hydrogen peroxide (DSHP) from H2 and O2. The sandwich-like AuPd nanoalloy comprising 1 wt % nanoparticle of an equimolar mixture of Au and Pd with 6 wt % GO and 93 wt % TiO2 supports shows a promising catalytic performance toward the DSHP reaction with H2O2 productivity and selectivity of 5.50 mol H2O2 gmetal-1 h-1 and 64%, respectively. The catalyst is found to be considerably more active than those reported in the literature. Furthermore, the H2O2 selectivity of the catalyst is found to improve considerably to 88% when the TiO2 support is pretreated by HNO3. It is found that the perimeter sites of the interface of AuPd alloy and TiO2 are deemed as catalytically active sites for the DSHP reactions and the acidic property of TiO2 can retard the other overreactions and the decomposition of yielded H2O2. Results of the present study may provide a design strategy for partially covered catalysts that are confined by 2D materials for selective reactions.

14.
J Chem Phys ; 148(19): 193830, 2018 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-30307224

RESUMO

Many ionic liquids show behavior similar to that of glassy systems, e.g., large and long-lasted deviations from Gaussian dynamics and clustering of "mobile" and "immobile" groups of ions. Herein a time-dependent four-point density correlation function-typically used to characterize glassy systems-is implemented for the ionic liquids, choline acetate, and 1-butyl-3-methylimidazolium acetate. Dynamic correlation beyond the first ionic solvation shell on the time scale of nanoseconds is found in the ionic liquids, revealing the cooperative nature of ion motions. The traditional solvent, acetonitrile, on the other hand, shows a much shorter length-scale that decays after a few picoseconds.

15.
J Phys Chem B ; 122(42): 9747-9756, 2018 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-30251841

RESUMO

Potential model descriptions for alkylsulfonic acids, methanesulfonic, ethanesulfonic, and propanesulfonic acids, are developed based on CHARMM and OPLS parameters and protocols. Thermodynamic, structural, and transport properties of these alkylsulfonic acids, including density, heat of vaporization, radial and spatial distribution functions, hydrogen bond structure, shear viscosity, and translational diffusion coefficients, are examined via molecular dynamics simulations using these potential models. The results are compared with the predictions of ab initio molecular dynamics simulations as well as with available experimental information. A good overall agreement indicates that the force-field descriptions developed here provide a reliable framework to study liquid systems containing alkylsulfonic acids.

16.
Phys Chem Chem Phys ; 20(29): 19339-19349, 2018 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-29989138

RESUMO

Reaction pathways for CS2 and COS in the ionic liquid, 1-ethyl-3-methylimidazolium (EMI+) acetate (OAc-), are studied using the ab initio self-consistent reaction field theory (SCRF) and molecular dynamics (MD) computer simulations. It is found that while CS2 converts to COS nearly at the 100% level through S/O exchange with acetate, both conversion and capture processes are kinetically possible for COS, yielding CO2/thioacetate and 1-ethyl-3-methylimidazole-2-thiocarboxylate (EMI-COS)/acetic acid as reaction products, respectively. These findings are in excellent agreement with recent experimental observations in the closely related 1-butyl-3-methylimidazolium acetate (BMI+OAc-) ionic liquid system. Constrained ab initio MD indicates that the capture reaction of COS (and CS2 if allowed) proceeds in a concerted fashion; viz., proton transfer from EMI+ to OAc- and carboxylation of EMI+ by COS (and CS2) occur concurrently, analogous to the concerted pathway proposed recently for CO2 capture in the imidazolium acetate ionic liquid family. As N-heterocyclic carbene (NHC) is not required, the concerted mechanism is fully consistent with the experimental fact that NHC has not been detected directly in this ionic liquid family. Computational analysis further predicts that if NHC would be present in the ionic liquid, it would react with CS2 and produce 1-ethyl-3-imidazole-2-dithiocarboxylate, prior to the conversion of CS2 to COS. Since such a dithiocarboxylate compound was not detected experimentally, the present analysis lends support to the view that NHC is not formed in the pure imidazolium acetate ionic liquid family.

17.
Nat Commun ; 9(1): 744, 2018 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-29467372

RESUMO

We report the synthesis and crystal structure of a nanocluster composed of 23 silver atoms capped by 8 phosphine and 18 phenylethanethiolate ligands. X-ray crystallographic analysis reveals that the kernel of the Ag nanocluster adopts a helical face-centered cubic structure with C2 symmetry. The thiolate ligands show two binding patterns with the surface Ag atoms: tri- and tetra-podal types. The tetra-coordination mode of thiolate has not been found in previous Ag nanoclusters. No counter ion (e.g., Na+ and NO3-) is found in the single-crystal and the absence of such ions is also confirmed by X-ray photoelectron spectroscopy analysis, indicating electrical neutrality of the nanocluster. Interestingly, the nanocluster has an open shell electronic structure (i.e., 23(Ag 5s1)-18(SR) = 5e), as confirmed by electron paramagnetic resonance spectroscopy. Time-dependent density functional theory calculations are performed to correlate the structure and optical absorption/emission spectra of the Ag nanocluster.

18.
Cancer Cell ; 32(6): 777-791.e6, 2017 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-29198913

RESUMO

Monoclonal antibodies (mAbs) can destroy tumors by recruiting effectors such as myeloid cells, or targeting immunomodulatory receptors to promote cytotoxic T cell responses. Here, we examined the therapeutic potential of combining a direct tumor-targeting mAb, anti-CD20, with an extended panel of immunomodulatory mAbs. Only the anti-CD27/CD20 combination provided cures. This was apparent in multiple lymphoma models, including huCD27 transgenic mice using the anti-huCD27, varlilumab. Detailed mechanistic analysis using single-cell RNA sequencing demonstrated that anti-CD27 stimulated CD8+ T and natural killer cells to release myeloid chemo-attractants and interferon gamma, to elicit myeloid infiltration and macrophage activation. This study demonstrates the therapeutic advantage of using an immunomodulatory mAb to regulate lymphoid cells, which then recruit and activate myeloid cells for enhanced killing of mAb-opsonized tumors.


Assuntos
Anticorpos Monoclonais/farmacologia , Antineoplásicos/farmacologia , Linfoma/imunologia , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/agonistas , Animais , Anticorpos Monoclonais Humanizados , Humanos , Imunoterapia/métodos , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Ativação de Macrófagos/efeitos dos fármacos , Ativação de Macrófagos/imunologia , Camundongos , Camundongos Transgênicos
19.
Nat Commun ; 8(1): 848, 2017 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-29018255

RESUMO

It has long been a challenge to dope metal nanoparticles with a specific number of heterometal atoms at specific positions. This becomes even more challenging if the heterometal belongs to the same group as the host metal because of the high tendency of forming a distribution of alloy nanoparticles with different numbers of dopants due to the similarities of metals in outmost electron configuration. Herein we report a new strategy for shuttling a single Ag or Cu atom into a centrally hollow, rod-shaped Au24 nanoparticle, forming AgAu24 and CuAu24 nanoparticles in a highly controllable manner. Through a combined approach of experiment and theory, we explain the shuttling pathways of single dopants into and out of the nanoparticles. This study shows that the single dopant is shuttled into the hollow Au24 nanoparticle either through the apex or side entry, while shuttling a metal atom out of the Au25 to form the Au24 nanoparticle occurs mainly through the side entry.Doping a metal nanocluster with heteroatoms dramatically changes its properties, but it remains difficult to dope with single-atom control. Here, the authors devise a strategy to dope single atoms of Ag or Cu into hollow Au nanoclusters, creating precise alloy nanoparticles atom-by-atom.

20.
BJU Int ; 120(5): 682-688, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28632935

RESUMO

OBJECTIVES: To assess the correlation of the resected and ischaemic volume (RAIV), which is a preoperatively calculated volume of nephron loss, with the amount of postoperative renal function (PRF) decline after minimally invasive partial nephrectomy (PN) in a multi-institutional dataset. PATIENTS AND METHODS: We identified 348 patients from March 2005 to December 2013 at six institutions. Data on all cases of laparoscopic (n = 85) and robot-assisted PN (n = 263) performed were retrospectively gathered. Univariable and multivariable linear regression analyses were used to identify the associations between various time points of PRF and the RAIV, as a continuous variable. RESULTS: The mean (sd) RAIV was 24.2 (29.2) cm3 . The mean preoperative estimated glomerular filtration rate (eGFR) and the eGFRs at postoperative day 1, 6 and 36 months after PN were 91.0 and 76.8, 80.2 and 87.7 mL/min/1.73 m2 , respectively. In multivariable linear regression analysis, the amount of decline in PRF at follow-up was significantly correlated with the RAIV (ß 0.261, 0.165, 0.260 at postoperative day 1, 6 and 36 months after PN, respectively). This study has the limitation of its retrospective nature. CONCLUSION: Preoperatively calculated RAIV significantly correlates with the amount of decline in PRF during long-term follow-up. The RAIV could lead our research to the level of prediction of the amount of PRF decline after PN and thus would be appropriate for assessing the technical advantages of emerging techniques.


Assuntos
Neoplasias Renais/cirurgia , Rim , Nefrectomia , Tratamentos com Preservação do Órgão , Cuidados Pré-Operatórios/métodos , Adulto , Idoso , Feminino , Taxa de Filtração Glomerular , Humanos , Rim/fisiopatologia , Rim/cirurgia , Neoplasias Renais/fisiopatologia , Masculino , Pessoa de Meia-Idade , Nefrectomia/métodos , Nefrectomia/estatística & dados numéricos , Tratamentos com Preservação do Órgão/métodos , Tratamentos com Preservação do Órgão/estatística & dados numéricos , Estudos Retrospectivos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA