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关键词： Interfaces   Physical chemistry   Cluster chemistry   Biomaterials   Spectroscopy  

关键词： Dynamic light scattering  

摘要： Every year the incidence of cancer and the death rate are increasing worldwide. The drug 8-hydroxyquinoline platinum(ii) [PtCl(8-O-quinoline)(dmso)] (8HQ-Pt) has been identified as a promising antitumor complex. Nanostructured lipid carriers (NLC) are second-generation drug nanocarrier systems that have superior advantages over other kinds of colloidal carrier systems. 8HQ-Pt compound loaded NLC formulations of cetyl esters (SS) were synthesized via ultrasonication in the presence of two different liquid oils: capric triglyceride, or olive oil. The physicochemical and microscopic characterizations of NLC were analyzed via dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). In vitro drug release and cytotoxicity, cell uptake and apoptosis assays against the human colon cancer cell line HT-29 were investigated. The results showed that NLCs indicated a narrow size distribution and a mean particle diameter in the range of 136-159 nm. The thermal characteristic analysis confirmed the stability of NLCs up to 185 degrees C. Encapsulation efficiencies of the 8HQ-Pt compound in NLCs were about 80% and the 8HQ-Pt compound in the formulations showed a controlled release profile during 72 h. The release profiles of these two different formulations and the antitumor effect on the HT-29 cell line were compared with those of the free 8HQ-Pt compound. The cellular uptake of two different NLC groups was proved by fluorescence microscopy and the presence of capric triglyceride liquid oil in the formulation increased the intracellular drug delivery capacity when compared with olive oil.

关键词： Transport properties  

摘要： Thermodiffusion in liquids (the Soret effect) has several unusual properties. In particular, transport can occur with or against a temperature gradient depending on the case. Numerous empirical correlations have been proposed with mixed success or range of applicability. Here, we show that physicochemical mechanics, derived from the Smoluchowski equation as a description of diffusive transport phenomena, is in accord with the experimental and simulated thermodiffusion data from colloidal beads and biomacromolecules to ionic solutions and ultracold fluid mixtures. It yields a simple formula for the Soret coefficient S-T based on the reference molar entropy including non-ideality. Hydrodynamic and local non-equilibrium effects are discussed but not included as these are apparently not a major contribution for the wide range of solutes under the near-equilibrium experimental conditions considered here.

关键词： Solvents  

摘要： Water-in-salt solutions, i.e. solutions in which the amount of salt by volume or weight is larger than that of the solvent, are attracting increasing attention in electrochemistry due to their distinct features that often include decomposition potentials much higher than those of lower concentration solutions. Despite the high solubility of potassium acetate (KAC) in water at room temperature (up to 25 moles of salt per kg of solvent), the low cost, and the large availability, the use of highly concentrated KAC solutions is still limited to a few examples in energy storage applications and a systematic study of their physical-chemical properties is lacking. To fill this gap, we have investigated the thermal, rheological, electrical, electrochemical, and spectroscopic features of KAC/water solutions in the compositional range between 1 and 25 mol kg(-1). We show the presence of a transition between the "salt-in-solvent" and "solvent-in-salt" regimes in the range of 10-15 mol kg(-1). Among the explored compositions, the highest concentrations (20 and 25 mol kg(-1)) exhibit good room temperature conductivity values (55.6 and 31 mS cm(-1), respectively) and a large electrochemical potential window (above 2.5 V).

关键词： Bamboo   Dimensional stability   Esterification   Treatment  

摘要： The effect of environmentally friendly treatment using citric acid and boron compounds on the physical-chemical and mechanical properties and thermal degradation of D. asper bamboo was investigated. The chemical modification using citric acid reduced the moisture uptake of bamboo by 32%, the water absorption by 26%, and thickness and width swelling by 43% and 31%, respectively, in comparison with the reference. FTIR analysis revealed the effect of the esterification process with an increase of the carbonyl/hydroxyl absorbance ratio, which explains the reductions in water absorption and swelling. No significant change was identified on the cellulose crystallinity determined by XRD, with only a small increase of the boron-treated samples. TG/DSC measurements showed that boron compounds cause a reduction of weight loss and decrease the exothermic heat flow upon heating under synthetic air flow. However, the modification with citric acid caused slightly higher thermal degradation in the same conditions of testing, which was overcome by the addition of boron compounds in the treatment solution. Enhanced mechanical performance was observed on bamboo samples treated only with boron compounds, while samples chemically modified by citric acid presented no changes or a small increase in compression and bending properties. Nevertheless, fibre detachment and structural changes on hemicellulose/cellulose caused a small decrease in shear strength and a considerable decrease, about 30%, in tensile strength. The overall results provided an insightful understanding regarding the chemical modification of bamboo, revealing new possibilities of treatment for the improvements of dimensional and thermal stability without the use of hazardous chemicals. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Crop residue   Microwave-assisted hydrothermal carbonization   Temperature   Ultrafine grinding   Phosphoric acid catalysis   Hydrochar  

摘要： We studied the effects of temperature (180-260 degrees C) and catalytic methods (ultrafine grinding and phosphoric acid treatment) on the microwave-assisted hydrothermal carbonization of crop residues by taking rice straw, corn stover and rape stalk as the research materials. The physicochemical and structural properties of hydrochars and liquid products generated under different conditions were characterized. The results showed that with increasing temperature, the hydrochar yield of crop residues decreased from 62.97-83.09% to 42.73-57.38%;the liquid yield rose from 15.03-33.38% to 37.94-47.58%;and the gas yield increased from 1.88-4.92% to 4.68-10.90%. The liquid products were all acidic (pH = 2.53-4.40), and the NH4+-N and PO43-P concentrations respectively showed an upward trend and downward trend with increasing temperature. Higher temperature led to enhanced carbonization degree, causing decreases in H/C and O/C atomic ratios but increases in higher heating value (HHV). Hydrochars prepared at 240 degrees C had the most intensified oxygenated functional groups, the largest specific surface area (5.5652-15.5058 m(2)/g), total pore volume (0.0403-0.1116 cm(3)/g) and mesopore volume (0.0395-0.1101 cm(3)/g), and the most carbon microspheres. However, temperature had a rather limited effect on the micropore volume of hydrochars derived from the three types of crop residues. Both ultrafine grinding and phosphoric acid catalysis could enhance hydrochar properties, with the latter being the more low-cost and efficient method. Hydrochars from ultrafine grinding crop residues had the highest peak strength of oxygenated functional groups, while those from phosphoric acid catalysis had higher fixed carbon (23.58-35.91%), C (45.03-65.50%) and HHV (17.45-27.18 MJ/kg), and lower ash content (4.21-15.67%), as well as the largest specific surface area (6.9140-15.5058 m(2)/g), total pore volume (0.0638-0.1116 cm(3)/g), micropore volume (0.0007-0.0015 cm(3)/g) and mesopore volum

关键词： Isotherms   Adsorption   Hysteresis   Clay   Minerals  

摘要： Mudstone can store formation water when acting as a caprock, which is a part of water sources in early oil exploitation. To improve crude oil quality, it is necessary to understand readsorption behavior of water. The behavior of water is closely related to the physicochemical structure of mudstone. Interactions between water and chemical structures are hard to detect because of the overlap of O-H infrared vibration bands (IR) in H2O and that in mudstone, thus D2O was innovatively used to interact with mudstone. In this study, mineral compositions and pore structures of mudstone were identified by X-ray diffraction, Xray fluorescence, and low-temperature N-2 adsorption/desorption, respectively. Furthermore, water retention contents at different relative humidities (RH) were investigated by comparing hysteresis loop areas at low (S-1) and high (S-2) RH based on water adsorption/desorption isotherms. Interactions between water and mudstone were investigated by studying the IR spectra changes and release of D, HD, OD, and HOD during drying of mudstones containing adsorbed D2O using in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and thermogravimetric coupled with mass spectrometry (TG-MS), respectively. The results showed that the specific surface area (S-BET) and mineral compositions controlled S-1, while S-2 was related to capillary pore volume. The detection of OD and HOD by in situ DRIFT at 300 degrees C and by TG-MS at 450 degrees C manifested that hydrogen bonds were formed between water and mudstone. Based on this study, we suggested that production wells should be constructed as far as possible on top of mudstone caprocks with relatively lower pore volumes and higher kaolinite contents to improve crude oil quality in early exploitation.

关键词： Diabetes   Amylin   Insulin coformulations   Rational drug design   Monte Carlo   Protein-protein interactions   Aggregation  

摘要： Injections of insulin are the main treatment for diabetes, but in the long run this therapy can induce serious drawbacks. This has inspired new drugs able to decrease insulin requirements. For instance, human amylin (hIAPP) is a small hormone cosecreted by pancreatic beta -cells with insulin to which is a synergistic partner. However, the high amyloidogenicity of hIAPP precluded it as a therapeutics and led to the design of pramlintide (sIAPP), a chimeric analogue with substitutions (A25P, S28P, and S29P) inherited from the aggregation-resistant rat isoform (rIAPP). Despite sIAPP advantages, it still shares with hIAPP a poorly soluble profile at physiological pH that hampers its mixture with insulin. Recent improvements, as charge-enhanced mutants, have been proposed. For instance, sIAPP(+) was screened in silico by purely microcanonical thermostatistical methods and adds to sIAPP an S20R mutation to uplift its solubility. This suggests that such physically inspired computational approach may also be auspicious on devising effective coformulations of insulin with amylin analogues. In this seminal attempt, we make comparative multicanonical simulations of regular acting human insulin coformulated with hIAPP, sIAPP, or sIAPP(+). To assess the respective physicochemical stabilities against aggregation, we characterize the structural-phase transitions through the microcanonical thermodynamic formalism and evaluate their time lags using the classical nucleation theory. These results are then correlated with estimates of solvation free energies, modeled by the Poisson-Boltzmann equation, and structural propensities. Experimental essays are compared to our simulations and support our methodology.

关键词： ion mobility-mass spectrometry   synthetic polymers   physicochemical properties   drug delivery   collision cross-section fitting  

摘要： Ion mobility-mass spectrometry (IM-MS) experiments are mostly used hand in hand with computational chemistry to correlate mobility measurements to the shape of the ions. Recently, we developed an automatable method to fit IM data obtained with synthetic homopolymers (i.e., collision cross sections;CCS) without resorting to computational chemistry. Here, we further develop the experimental IM data interpretation to explore physicochemical properties of a series of nine polymers and their monomer units by monitoring the relationship between the CCS and the degree of polymerization (DP). Several remarkable points of the CCS evolutions as a function of the DP were found: the first observed DP of each charge state (.DPfirst DP), the DPs constituting the structural rearrangements (.DPrearr), and the DPs at the half-rearrangement (DPhalf-rearr). Given that these remarkable points do not rely on absolute CCS values, but on their relative evolution, they can be extracted from CCS or raw IM data without accurate IM calibration. Properties such as coordination numbers of the cations, steric hindrance, or side chain flexibility can be compared. This leads to fit parameter predictions based on the nature of the monomer unit. The interpretation of the fit parameters, extracted using solely experimental data, allows a rapid screening of the properties of the polymers.

关键词： Alcohols   Liquids   Ions   Ionization   Solvents  

摘要： The relative contributions to ionization efficiency by three molecular chemical properties have been examined for field-free and field-enabled capillary vibrating sharp-edge spray ionization (cVSSI) using mass spectrometry (MS) analysis. Ion intensities have been recorded for model compounds under each operational ionization mode as well as for aqueous and nonaqueous (methanol) solvent systems. Multiple regression analysis suggests that for field-free cVSSI, ion intensity is mostly associated with the log of the base dissociation constant (pK(b)) and proton affinity (PA) for both aqueous and methanol solutions. Comparatively, for field-enabled cVSSI using aqueous solutions, the dominant factor correlated with ion intensity is the log of the partition coefficient (log P). To a lesser degree, this is observed for methanol solutions as well. For ESI, pK(b) is the dominant factor associated with ion signal levels from methanol and aqueous solutions. These results are supported by studies conducted on two different mass spectrometers employing different cVSSI emitter tips. The relationship of ion intensity and pK(b) in ESI is supported by multiple studies;however, the shift to other chemical properties with the addition of cVSSI suggests the possibility that a different (or combinations of) ionization mechanism(s) may be operative for these ionization modes. These results are briefly considered in light of the different ESI mechanisms. [Graphics]