Search results for "Effects"
showing 10 items of 2634 documents
Eckhaus instability of stationary patterns in hyperbolic reaction–diffusion models on large finite domains
2022
AbstractWe have theoretically investigated the phenomenon of Eckhaus instability of stationary patterns arising in hyperbolic reaction–diffusion models on large finite domains, in both supercritical and subcritical regime. Adopting multiple-scale weakly-nonlinear analysis, we have deduced the cubic and cubic–quintic real Ginzburg–Landau equations ruling the evolution of pattern amplitude close to criticality. Starting from these envelope equations, we have provided the explicit expressions of the most relevant dynamical features characterizing primary and secondary quantized branches of any order: stationary amplitude, existence and stability thresholds and linear growth rate. Particular em…
New Internal-Charge-Transfer Second-Order Nonlinear Optical Chromophores Based on the Donor Ferrocenylpyrazole Moiety
2016
A series of new N-arylated ferrocenepyrazole structures, carrying different donor or acceptor substituents in the para position of the aryl ring, has been synthesized by the Chan-Lam cross-coupling reaction. The nonplanar geometric molecular structure of some of these chromophores together with their crystal packing was determined by X-ray diffraction, and the HOMO and LUMO energy levels were evaluated by electrochemical and optical measurements and by density functional theoretical (DFT) calculations. By the investigation of solvent effects and time-dependent DFT (TD-DFT) calculations, the intense electronic absorption band around 270-310 nm was confirmed to be an internal-chargetransfer (…
Site-specific halloysite functionalization by polydopamine: A new synthetic route for potential near infrared-activated delivery system
2022
Abstract Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demo…
Amidase-responsive controlled release of antitumoral drug into intracellular media using gluconamide-capped mesoporous silica nanoparticles
2012
MCM-41 silica nanoparticles were used as inorganic scaffolding to prepare a nanoscopic-capped hybrid material S1, which was able to release an entrapped cargo in the presence of certain enzymes, whereas in the absence of enzymes, a zero release system was obtained. S1 was prepared by loading nanoparticles with Safranine O dye and was then capped with a gluconamide derivative. In the absence of enzymes, the release of the dye from the aqueous suspensions of S1 was inhibited as a result of the steric hindrance imposed by the bulky gluconamide derivative, the polymerized gluconamide layer and the formation of a dense hydrogen-bonded network around the pore outlets. Upon the addition of amidase…
Monitoring pH and ORP in a SHARON reactor
2011
This paper analyses the valuable information provided by the on-line measurements of pH and oxidation reduction potential (ORP) in a continuous single high ammonia removal over nitrite (SHARON) reactor. A laboratory-scale SHARON reactor equipped with pH, ORP, electric conductivity and dissolved oxygen (DO) probes has been operated for more than one year. Nitrogen removal over nitrite has been achieved by adding methanol at the beginning of anoxic stages. Time evolution of pH and ORP along each cycle allows identifying the decrease in nitritation rate when ammonia is consumed during the aerobic phase and the end of the denitrification process during the anoxic phase. Therefore, monitoring pH…
Experimental and theoretical studies on polar Diels–Alder reactions of 1-nitronaphathalene developed in ionic liquids
2013
The reactions between 1-nitronaphthalene 1 and two nucleophilic dienes, Danishefsky´s diene 2 and 1-trimethylsilyloxy-1,3-butadiene 3, to yield phenanthrenols 7 and 8 developed in protic and aprotic ionic liquids (ILs) with an imidazolium cation base permit to conclude that the reactions occur in better experimental conditions than in molecular solvents. The yields obtained with protic ILs are better than those observed with aprotic ILs. In this sense, the higher yields obtained with aprotic ILs, (working at 60ºC, 48 h) are comparable with the lower yields observed in protic ILs (60 ºC, 24 h). DFT calculations for the reaction of 1-nitronaphthalene 1 with diene 3, in the absence and in the …
Laser spectroscopy measurement of the 2s-hyperfine splitting in lithium-like bismuth
2017
We have recently reported on the first direct measurement of the $2s$ hyperfine transition in lithium-like bismuth (209Bi80+) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. Combined with a new measurement of the $1s$ hyperfine splitting (HFS) in hydrogen-like (209Bi82+) the so-called specific difference ${\rm{\Delta }}^{\prime} E=-61.37(36)$ meV could be determined and was found to be in good agreement with its prediction from strong-field bound-state quantum electrodynamics. Here we report on additional investigations performed to estimate systematic uncertainties of these results and on details of the experimental setup. We show that the dominating uncertainty a…
Robust Fault Detection of Linear Uncertain Time-Delay Systems Using Unknown Input Observers
2013
This paper deals with the problem of fault detection for linear uncertain time-delay systems. The proposed method for Luenberger observers is developed for unknown input observers (UIOs), and a novel procedure for the design of residual based on UIOs is presented. The design procedure is carried out based on the ${H}_{\infty }$ model matching approach which minimizes the difference between generated residuals by the optimal observer and those by the designed observer in the presence of uncertainties. The optimal observer is designed for the ideal system and works so that the fault effect is maximized while the exogenous disturbances and noise effects are minimized. This observer can give di…
Effectiveness of substituting cyclosporin A with tacrolimus in reducing gingival overgrowth in renal transplant patients
2009
Objectives: this study aims to evaluate the effectiveness of periodontal therapy combined with tacrolimus in the suppression of gingival overgrowth (GO) and the effect on GO of changing from cyclosporin A to tacrolimus. Patients and methods: sixteen renal transplant patients, averaging 52 years of age, whose kidney function was stable and were receiving treatment with cyclosporin A, were randomly assigned to one of two groups. In the experimental group, patients were instructed in oral hygiene and underwent periodontal treatment, whereas in the control group, only oral hygiene instructions were given. After the first visit and the change of medication from cyclosporine to tacrolimus in both…
‘If-then’ but when? Effects of implementation intentions on children’s and adolescents’ prospective memory
2021
Abstract Prospective memory (PM), the ability to initiate and implement delayed intentions, increases across childhood and adolescence. Previous evidence on older adults indicated beneficial effects of implementation intentions (an encoding strategy) on individuals’ PM performance; especially when cognitive control demands were high and availability of cognitive resources low. This research program set out to investigate the impact of implementation intentions on children’s and adolescents’ PM while simultaneously varying cognitive control demands of the PM paradigm. Across two studies, implementation intention encoding was contrasted with standard encoding. In addition, Study 1 manipulated…