We study boundedness properties of a class ofmultiparameter paraproducts on the dual space of the dyadic Hardy space Hd1 (T N), the dyadic product BMO space BMOd (T N). For this, we introduce a notion of logarithmic mean oscillation on the polydisc. We also obtain a result on the boundedness of iterated commutators on BMO [0, 1]N). 相似文献
A papillary‐structured collagen fibril membrane is created, mimicking the 3D‐architecture of the human papillary dermis. Primary human keratinocytes cultured to confluency on papillar‐structured films are compared to keratinocytes cultured on flat membranes. Microscopical evaluation reveals the presence of morphologically distinct cells at the base of the papillar structures that are not observed on flat membranes. Gene expression microarrays and RT‐qPCR indicate that these cells are in a more proliferative/migrational state, whereas cells on flat membranes have a more differentiated expression profile. Immunohistochemical stainings confirm these results. In conclusion, specific collagen architecture can direct keratinocyte behavior, and this may be used to further improve skin regeneration.
Vacuolar ATPases are a potential therapeutic target because of their involvement in a variety of severe diseases such as osteoporosis or cancer. Archazolide A (1) and related analogs have been previously identified as selective inhibitors of V-ATPases with potency down to the subnanomolar range. Herein we report on the determination of the ligand binding mode by a combination of molecular docking, molecular dynamics simulations, and biochemical experiments, resulting in a sound model for the inhibitory mechanism of this class of putative anticancer agents. The binding site of archazolides was confirmed to be located in the equatorial region of the membrane-embedded V(O)-rotor, as recently proposed on the basis of site-directed mutagenesis. Quantification of the bioactivity of a series of archazolide derivatives, together with the docking-derived binding mode of archazolides to the V-ATPase, revealed favorable ligand profiles, which can guide the development of a simplified archazolide analog with potential therapeutic relevance. 相似文献
The aim of this work is to report phase equilibrium data for the binary systems (CO2 + α-humulene) and (CO2 + trans-caryophyllene), and for the ternary system (CO2 + α-humulene + trans-caryophyllene). Results from literature show that α-humulene and trans-caryophyllene are the main compounds responsible for the anti-inflammatory and anti-allergic characteristics attributed to the medicinal plant Cordia verbenacea D.C., hence giving importance to the phase behaviour investigation performed in this work. Phase equilibrium experiments were performed in a high-pressure, variable-volume view cell over the temperature range of T = (303 to 343) K and pressures up to 20 MPa. (Liquid + liquid) and (vapour + liquid + liquid) equilibrium were observed at T = 303 K, while (vapour + liquid) phase transitions were verified to occur from T = (313 to 343) K, for all systems studied. Thermodynamic modelling was performed using the Peng–Robinson equation of state and the classical quadratic mixing rules, with a satisfactory agreement between experimental and calculated values. 相似文献
Alkene content determinations in fluid catalytic cracking (FCC) liquid products were performed by means of normal-phase high-performance liquid chromatography (NP-HPLC) with diode array detection (UV/DAD). Separation of alkenes from aromatic hydrocarbons was performed on amino-modified silica gel column with n-heptane as mobile phase. The column has a little affinity to alkenes and saturated hydrocarbons and a pronounced affinity to aromatic compounds. The problem of alkenes and saturates co-elution on this column type was overcome with the detection system, UV/DAD, sensitive and selective to alkenes, while saturates are inactive in UV field. Total alkene content was determined as a sum of mono- and dialkene groups quantified by external standard method. Validation and verification of the developed method proved their applicability. The following criteria were used to validate the HPLC–DAD method: selectivity, linearity, precision, limits of detection and quantification. Alkene contents were quantified with the external standard method of wide calibration range, so both low and high alkene contents can be determined by the single calibration. Correlation coefficients were higher than 0.99. Precision was evaluated as repeatability and intermediary precision with relative standard deviations less than 5%. Some structural investigation of alkene groups was performed to confirm the assumption. Proposed method was compared with certified NMR method. Six commercial motor gasoline samples were analyzed by these two methods. Obtained results indicate good agreement between alkene content determined by both methods. The developed method was applied to the determination of alkene content in liquid FCC products in the boiling range from 70 °C to 190 °C. 相似文献
Several organo-modified montmorillonites were studied to prepare nanocomposites of polyoctamethylene suberate, a biodegradable polyester. Mixtures were analyzed by conventional powder X-ray diffraction and transmission electron microscopy techniques. C30B clay was effective in rendering an intercalated structure with rather variable silicate layer spacing. The hydroxyl groups of the organo-modifier may allow the establishment of good interactions with the polar carbonyl groups of the studied polyester. A slight decrease in thermal stability was detected when the modified clay was incorporated into the polymer matrix. Isothermal and nonisothermal crystallization kinetics were studied by DSC and results compared with those for the neat polyester. The overall crystallization rate determined by calorimetric methods depends on the nucleation density and the crystal growth rate, which were independently evaluated by means of optical microscopy. Crystallization and morphological features were also analyzed by simultaneous SAXS/WAXD measurements made at a selected crystallization temperature and cooling rate under both isothermal and nonisothermal conditions, respectively. 相似文献
One of the main limits in the use of block copolymers for nanotechnological applications lies in the poor control over the alignment of the nanoscopic domains. The self-assembling behavior of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) has been modified by stoichiometric complexation of the ethylene oxide units with resorcinol and a simple procedure to prepare nanostructured films with normally oriented cylinders is reported. By direct spin coating of a series of complexated PS-b-PEO samples with different molecular weight and composition, films with the same morphology and orientation (i.e., normally oriented packed cylinders) have been obtained, also when different nanostructures and alignments were expected on the basis of the volume fraction composition and self-assembling behavior of pure copolymers. Tuning of the cylinder diameters in the range from 20 to 50 nm was possible by varying the length of the PEO block. The effects of resorcinol complexation have been studied by differential scanning calorimetry and X-ray diffraction and the morphologies of PS-b-PEO and PS-b-PEO/resorcinol films have been monitored by atomic force microscopy and electron microscopies. DSC and XRD analyses demonstrate that resorcinol significantly influences the crystallization behavior of the PEO block. The varied interfacial and surface energies of the PEO domains and the overall reduction of the crystalline phase in PS-b-PEO/resorcinol films appear to be strictly related to the morphological changes occurring by complexation. 相似文献
The present work describes the plasma polymerisation of acrylic acid at atmospheric pressure. The influence of two operating
parameters (monomer concentration and discharge power) on the properties of the deposited films is investigated. Results show
that at a monomer concentration of 2.5 ppm and a discharge power of 9.5 W, the monomer is only slightly fragmented leading
to a high amount of carboxylic acid groups on the deposited films. In contrast, when monomer concentration is decreased or
discharge power increased, the incidence of monomer fragmentation processes is higher, leading to a lower amount of carboxylic
acid groups on the films. This behaviour can be explained by a higher energy amount available per monomer molecule at low
monomer concentrations and high discharge powers and a higher flux of positive ions attacking the surface at high discharge
powers. Taking into account these results, it can be concluded that the deposition parameters should be carefully selected
in order to preserve the stability of the monomer and thus obtain coatings with high carboxylic acid densities. 相似文献