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1.
Arch. esp. urol. (Ed. impr.) ; 75(6): 544-551, Aug. 28, 2022. tab, graf
Article in Spanish | IBECS | ID: ibc-209635

ABSTRACT

Introduction and Objectives: Radical prostatectomy has an impact on urinary continence. Many factors are involved in continence. The objective of this study is evaluate the effect of guided Pelvic Floor Exercises prior to robotic radical prostatectomy (RRP) on the rate of urinary incontinence compared with written information. Material and Method: randomized study of 62 patients who are waiting for PRR. They were rondomized in two groups: experimental group (exercises guided by a physiotherapist) or a control group (written information). Primary objective was the continence rate measured by pad test and ICIQ-SF one month after the intervention, Secondary objectives were incontinence severity, quality of life with SF-36 and KHQ questionnaires and the correlation between incontinence and quality of life. Results: We found no differences in continence rate between groups after the intervention. We found differences in “emotional problems” and “personal relationships”, in favor of the control group. There is a correlation between the amount of urine leakage and age, urgency and all the domains of the KHQ questionnaire except general quality of life, as well as in the areas “energy/fatigue” and “social function” of the SF-36. Conclusions: Physiotherapist-guided exercises before RRP do not seem to offer advantages compared to written information, in terms of the incontinence rate and its severity one month after the surgery. Urinary incontinence is correlated with age, urgency, and deterioration in quality of life (AU)


Introducción y Objetivos: La prostatectomía radicaltiene un gran impacto en la continencia urinaria. Muchosfactores intervienen en la continencia. El objetivo de esteestudio es evaluar el efecto en la tasa de incontinencia deorina de los Ejercicios de Suelo Pélvicos guiados previos ala prostatectomía radical robótica (PRR), frente a la información escrita.Material y Método: Ensayo clínico en el que se incluyen 62 pacientes en lista de espera para PRR, aleatorizándolos a un grupo experimental (ejercicios guiados porfisioterapeuta) o control (información escrita). El objetivoprimario fue la tasa de continencia medida por test de compresa y el cuestionario ICIQ-SF al mes de la intervención,Fueron objetivos secundarios, la severidad de incontinencia, la calidad de vida con cuestionarios SF-36 y KHQ, y lacorrelación entre la incontinencia y la calidad de vida.Resultados: No encontramos diferencias en la tasade incontinencia entre los grupos tras la intervención. Encontramos diferencias en “problemas emocionales” y “relaciones personales”, a favor del grupo control. Existe correlación entre la cantidad de las pérdidas de orina y la edad,la urgencia miccional y todos los dominios del cuestionarioKHQ excepto la calidad de vida general, así como en lasáreas “energía/fatiga” y “función social” del SF-36.Conclusiones: Los ejercicios guiados por fisioterapeuta antes de PRR no parecen ofrecer ventajas frente ala información escrita, en la tasa de incontinencia y severidad de la misma al mes de la intervención. La incontinenciade orina se correlaciona con la edad, la urgencia miccionaly el deterioro en la calidad de vida. (AU)


Subject(s)
Humans , Male , Middle Aged , Aged , Robotic Surgical Procedures , Urinary Incontinence/etiology , Urinary Incontinence/prevention & control , Prostatectomy/methods , Treatment Outcome , Exercise Therapy , Pelvic Floor Disorders/rehabilitation , Quality of Life , Severity of Illness Index
2.
Sci Total Environ ; 737: 139638, 2020 Oct 01.
Article in English | MEDLINE | ID: mdl-32512297

ABSTRACT

Nowadays, India is the third-largest CO2 emitter and energy consumer in the world, and, it is soon expected to surpass China as the most populated country. Therefore, it is of great interest to analyse how India is developing its energy transition to a lower-carbon economy. This work analyses the evolution of the main driving forces of CO2 emissions in India during the period 1990-2016 through the use of an enlarged version of the Kaya identity, which establishes a link between CO2 emissions, types of energy sources (16), size of the economic sectors (3) and value of the Gross Domestic Product. India's CO2 emissions increased by 276% in the period under study, due to the rapid economic growth of India, which has been the dominating driving force contributing to the increase in CO2 emissions by 241%, while the energy intensity has been the main one reducing them by approximately -47%. So far, the use of coal has supported the rapid economic growth and the contribution of renewable energy, although significant, is still short compared to the total amount of energy employed. Remarkably, the estimated value of the emission intensity for 2020 supposes a 26% reduction concerning the value in 2005. According to this result, India is on the right pathway to fulfil its Nationally Determined Contribution but not to reduce its net CO2 emissions.

3.
BMC Urol ; 19(1): 92, 2019 Oct 16.
Article in English | MEDLINE | ID: mdl-31619215

ABSTRACT

BACKGROUND: Fatigue is one of the most prevalent symptoms among cancer patients. Specifically, in metastatic castration-resistant prostate cancer (mCRPC) patients, fatigue is the most common adverse event associated with current treatments. The purpose of this study is to describe the prevalence of fatigue and its impact on quality of life (QoL) in patients with CRPC in routine clinical practice. METHODS: This was a cross-sectional, multicentre study. Male chemo-naïve adults with high-risk non-metastatic (M0) CRPC and metastatic (M1) CRPC (mCRPC) were eligible. Fatigue was measured using the Brief Fatigue Inventory (BFI) and QoL was assessed using the Functional Assessment of Cancer Therapy questionnaire for patients with prostate cancer (FACT-P) and the FACT-General (FACT-G) questionnaire. Data were analysed using Mann-Whitney or Kruskal-Wallis tests (non-parametric distribution), a T-test or an ANOVA (parametric distribution) and the Fisher or chi-squared tests (categorical variables). RESULTS: A total of 235 eligible patients were included in the study (74 [31.5%] with M0; and 161 [68.5%] with M1). Fatigue was present in 74%, with 38.5% of patients reporting moderate-to-severe fatigue. Mean FACT-G and FACT-P overall scores were 77.6 ± 16.3 and 108.7 ± 21.4, respectively, with no differences between the CRPC M0 and CRPC M1 subgroups. Fatigue intensity was associated with decreased FACT-G/P scores, with no differences between groups. Among 151 mCRPC patients with available treatment data, those treated with abiraterone-prednisone ≥3 months showed a significant reduction in fatigue intensity (p = 0.043) and interference (p = 0.04) compared to those on traditional hormone therapy (HT). Patients on abiraterone-prednisone ≥3 months showed significantly better FACT-G/P scores than patients on HT (p = 0.046 and 0.018, respectively). CONCLUSION: Our data show a high prevalence and intensity of fatigue and its impact on QoL in chemo-naïve CRPC patients. There is an association between greater fatigue and less QoL, irrespective of the presence or absence of metastasis. Chemo-naïve mCRPC patients receiving more than 3 months of abiraterone acetate plus prednisone showed an improvement of fatigue and QoL when compared to those on traditional HT. TRIAL REGISTRATION: Not applicable since it is not an interventional study.


Subject(s)
Fatigue/epidemiology , Fatigue/etiology , Prostatic Neoplasms, Castration-Resistant/complications , Quality of Life , Aged , Aged, 80 and over , Cross-Sectional Studies , Humans , Male , Middle Aged , Prevalence
4.
Phys Chem Chem Phys ; 18(38): 26562-26571, 2016 Sep 29.
Article in English | MEDLINE | ID: mdl-27711470

ABSTRACT

ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a compound extensively employed to evaluate the free radical trapping capacity of antioxidant agents and complex mixtures such as biological fluids or foods. This evaluation is usually performed by using a colourimetric experiment, where preformed ABTS radical cation (ABTS˙+) molecules are reduced in the presence of an antioxidant causing an intensity decrease of the specific ABTS˙+ UV-visible absorption bands. In this work we report a strong effect of silver plasmonic nanoparticles (Ag NPs) on ABTS leading to the formation of ABTS˙+. The reaction of ABTS with Ag NPs has been found to be dependent on the interfacial and plasmonic properties of NPs. Specifically, this reaction is pronounced in the presence of spherical nanoparticles prepared by the reduction of silver nitrate with hydroxylamine (AgH) and in the case of star-shaped silver nanoparticles (AgNS). On the other hand, spherical nanoparticles prepared by the reduction of silver nitrate with citrate apparently do not react with ABTS. Additionally, the formation of ABTS˙+ is investigated by surface-enhanced Raman scattering (SERS) and the assignment of the most intense vibrational bands of this compound is performed. The SERS technique enables us to detect this radical cation at very low concentrations of ABTS (∼2 µM). Altogether, these findings allow us to suggest the use of ABTS/Ag NPs-systems as reliable and easy going substrates to test the antioxidant capacity of various compounds, even at concentrations much lower than those usually used in the spectrophotometric assays. Moreover, we have suggested that ABTS could be employed as a suitable agent to investigate the interfacial and plasmonic properties of the metal nanoparticles and, thus, to characterize the nanoparticle metal systems employed for various purposes.

5.
Chemotherapy ; 61(5): 249-55, 2016.
Article in English | MEDLINE | ID: mdl-26950478

ABSTRACT

New compounds with antituberculosis activity and their combination with classic drugs have been evaluated to determine possible interactions and antagonism. The aim of this study was to evaluate the in vitro activity of Casiopeínas® copper-based compounds (CasIIIia, CasIIIEa, and CasIIgly) alone and combined with isoniazid (INH), rifampicin, or ethambutol (EMB) against resistant and susceptible Mycobacterium tuberculosis. Seventeen clinical M. tuberculosis isolates (5 multi-drug resistant and 2 resistant to INH and/or EMB) were subjected to determination of the minimal inhibitory concentration (MIC) by the resazurin microtiter assay and combination assessment by the resazurin drug combination microtiter assay. The Casiopeínas® alone showed a remarkable effect against resistant isolates with MIC values from 0.78 to 12.50 µg/ml. Furthermore, a synergistic effect mainly with EMB is shown for both resistant and susceptible clinical isolates. Casiopeínas® are promising candidates for future investigation into the development of antituberculosis drugs, being one of the first examples of essential metal-based drugs used in this field.


Subject(s)
Antitubercular Agents/pharmacology , Coordination Complexes/pharmacology , Copper/chemistry , Mycobacterium tuberculosis/drug effects , Tuberculosis/microbiology , Antitubercular Agents/chemistry , Antitubercular Agents/therapeutic use , Coordination Complexes/chemistry , Coordination Complexes/therapeutic use , Drug Resistance, Bacterial/drug effects , Drug Synergism , Ethambutol/pharmacology , Ethambutol/therapeutic use , Humans , Isoniazid/pharmacology , Isoniazid/therapeutic use , Macrophages/cytology , Macrophages/drug effects , Macrophages/microbiology , Microbial Sensitivity Tests , Mycobacterium tuberculosis/isolation & purification , Rifampin/pharmacology , Rifampin/therapeutic use , Tuberculosis/drug therapy
6.
Phys Rev Lett ; 112(16): 162701, 2014 Apr 25.
Article in English | MEDLINE | ID: mdl-24815644

ABSTRACT

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

7.
Phys Chem Chem Phys ; 16(25): 12802-11, 2014 Jul 07.
Article in English | MEDLINE | ID: mdl-24836778

ABSTRACT

In this work we report the study of the chemical modifications undergone by flavonoids, especially by quercetin (QUC), under alkaline conditions by UV-visible absorption, Raman and surface-enhanced Raman scattering (SERS) spectroscopy, the study was performed in aqueous solution and also on Ag nanoparticles (AgNPs). Several processes are involved in the effect of alkaline pH both in solution and on AgNPs: autoxidation affecting mainly the C-ring of the molecule and giving rise to the molecular fragmentation leading to simpler molecular products, and/or the dimerization and further polymerization leading to species with a higher molecular weight. In addition, there exists a clear structure-instability correlation concerning mainly particular groups in the molecule: the C3-OH group in the C-ring, the catechol moiety in the B-ring and the C2=C3 bond also existing in the C-ring. QUC possesses all these groups and exhibits high instability in alkaline solution. The SERS spectra registered at different pH revealed a change in the dimerization protocol of QUC going from the A- and C-rings-like-condensation to B-ring-like-condensation. Increasing the knowledge of the chemical properties of these compounds and determining the structure-activity relationship under specific environmental factors allow us to improve their beneficial properties for health as well as the preservation of Cultural Heritage objects, for example, by preventing their degradation.


Subject(s)
Flavonoids/chemistry , Hydrogen-Ion Concentration , Quercetin/chemistry , Spectrophotometry, Ultraviolet/methods , Spectrum Analysis, Raman/methods
8.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(4 Pt 2): 046208, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21599271

ABSTRACT

We study the critical behavior of excited states and its relation to order and chaos in the Jaynes-Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excited-state quantum phase transitions demarcating the upper edge of the superradiant phase. For the Dicke model, the signatures of criticality in excited states are blurred by the onset of quantum chaos. We show that the emergence of quantum chaos is caused by the precursors of the excited-state quantum phase transition.

9.
Anal Chem ; 83(7): 2518-25, 2011 Apr 01.
Article in English | MEDLINE | ID: mdl-21391577

ABSTRACT

Silver nanoparticles (NPs) functionalized with the molecular assembler bis-acridinium dication lucigenin (LG) have been used as a chemical sensor system to detect a group of polycyclic aromatic hydrocarbon (PAH) pollutants in a multicomponent mixture by means of surface-enhanced raman scattering (SERS). The effectiveness of this system was checked for a group of PAHs with different numbers of fused benzene rings, namely anthracene, pyrene, triphenylene, benzo[c]phenanthrene, chrysene, and coronene. In order to determine the host capacity of this sensor system, the self-assembly of the LG viologen on a metallic surface has been checked by analyzing SERS intensities of PAH bands at different LG concentrations. The NP-LG-analyte affinity is derived from the analysis of PAH band intensities at different concentrations of pollutants, the adsorption isotherm of each PAH on NP-LG cavities has been studied, and the corresponding adsorption constants have been evaluated. The limit of detection at trace-level concentration is confirmed by the presence of their characteristic fingerprint vibrational bands. The SERS spectra of PAH mixtures confirm that LG viologen dication shows a higher analytical selectivity to PAHs constituted by four fused benzene rings, mainly pyrene and benzo[c]phenanthrene, in agreement with their higher affinity which is also related to their better fit into the intermolecular LG cavities. As a conclusion, SERS spectra recorded on modified NP-LG surfaces are a powerful chemical tool to detect organic pollutants.

10.
Langmuir ; 26(18): 14663-70, 2010 Sep 21.
Article in English | MEDLINE | ID: mdl-20799745

ABSTRACT

The adsorption of beta(2)-adrenergic agonist (ßAA) drugs clenbuterol, salbutamol, and terbutaline on metal surfaces has been investigated in this work by means of surface-enhanced Raman scattering (SERS). To assist in this investigation, a previous vibrational (IR and normal Raman) characterization of these drugs was performed, supported by ab initio density functional theory calculations. The application of SERS was aimed to apply this highly sensitive technique, based on localized surface plasmon resonance, in the detection of ßAA at trace concentrations and as a possible alternative method which can be postulated in routine antidoping analysis. The adsorption of these drugs was studied in depth at different experimental conditions: on Au and Ag, at different pHs, and with varying adsorbate concentration. Moreover, plasmon resonance spectroscopy was employed to investigate the adsorption of these drugs on the metal nanoparticles as well as their aggregation. It was found that the adsorption of these molecules is more effective on gold nanoparticles and at acidic pH, based on the direct interaction of the aromatic or aliphatic moieties through ionic or coordination bonds with the metal. These drugs followed a Langmuir adsorption model from which the adsorption constant and the limit of detection can be determined.


Subject(s)
Adrenergic beta-Agonists/analysis , Adrenergic beta-Agonists/chemistry , Doping in Sports , Metal Nanoparticles/chemistry , Adsorption , Gold/chemistry , Hydrogen-Ion Concentration , Silver/chemistry , Spectrum Analysis, Raman , Surface Properties , Vibration
11.
Phys Rev Lett ; 102(11): 112502, 2009 Mar 20.
Article in English | MEDLINE | ID: mdl-19392195

ABSTRACT

A generic procedure is proposed to construct many-body quantum Hamiltonians with partial dynamical symmetry. It is based on a tensor decomposition of the Hamiltonian and allows the construction of a hierarchy of interactions that have selected classes of solvable states. The method is illustrated in the SO(6) limit of the interacting boson model of atomic nuclei and applied to the nucleus 196Pt.

12.
Anal Chim Acta ; 624(2): 286-93, 2008 Aug 29.
Article in English | MEDLINE | ID: mdl-18706335

ABSTRACT

Organochlorine pesticide endosulfan has been detected for the first time by using surface-enhanced Raman scattering (SERS) at trace concentrations. The bis-acridinium dication lucigenine was successfully used as a molecular assembler in the functionalization of metal nanoparticles to facilitate the approach of the pesticide to the metal surface. From the SERS spectra valuable information about the interaction mechanism between the pesticide and lucigenin can be deduced. In fact, endosulfan undergoes an isomerization upon adsorption onto the metal, while the viologen undergoes a rotation of the acridinium planes to better accommodate the pesticide molecule. An interaction between the N atom of the central acridinium ring and the pesticide Cl-CC-Cl fragment is verified through a charge-transfer complex. The present study affords important information which can be applied to the design of chemical sensor systems of persistent organic pollutants based on the optical detection on functionalized metal nanoparticle.

13.
J Colloid Interface Sci ; 326(1): 103-9, 2008 Oct 01.
Article in English | MEDLINE | ID: mdl-18656205

ABSTRACT

Different Ag nanoparticles were prepared by four different methods (chemical reduction with trisodium citrate, chemical reduction with hydroxylamine hydrochloride, laser ablation and laser in situ photoreduction) to compare their applicability in surface-enhanced Raman scattering (SERS), their stability and other interfacial characteristics such as the pH, surface availability and the surface potential. This study was conducted by using the anthraquinone dye alizarin as a molecular probe since this molecule is able to be adsorbed onto the metal through three different forms, which relative proportions depend on the interfacial properties of the exposed metal surfaces.

14.
Anal Chim Acta ; 616(1): 69-77, 2008 May 26.
Article in English | MEDLINE | ID: mdl-18471486

ABSTRACT

Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) combined emissions were used in this work to the analysis of humic acids (HA). This study examined HA structure at different pH and HA concentrations and assessed the structural differences taking place in HA as a result of various amendment trials. Raman and fluorescence emissions behave in opposite ways due to the effect of the metal surface on the aromatic groups responsible for these emissions. The information afforded by these techniques can be successfully employed in the structural and dynamic analysis of these important macromolecules. The surface-enhanced emission (SEE) spectra, that is the sum of the Raman and the fluorescence emissions, were acquired by using both macro- and micro-experimental configurations in order to apply imaging and confocal Raman and fluorescence spectroscopy techniques on the analysis of HA.


Subject(s)
Humic Substances/analysis , Soil/analysis , Spectrum Analysis, Raman/instrumentation , Spectrum Analysis, Raman/methods , Fluorescence , Humic Substances/radiation effects , Hydrogen-Ion Concentration , Lasers , Particle Size , Reproducibility of Results , Sensitivity and Specificity , Spectrometry, Fluorescence , Surface Properties
15.
Phys Rev Lett ; 99(18): 182501, 2007 Nov 02.
Article in English | MEDLINE | ID: mdl-17995400

ABSTRACT

We have observed the two-proton radioactivity of the previously unknown (19)Mg ground state by tracking the decay products in-flight. For the first time, the trajectories of the 2p-decay products, (17)Ne+p+p, have been measured by using tracking microstrip detectors which allowed us to reconstruct the 2p-decay vertices and fragment correlations. The half-life of (19)Mg deduced from the measured vertex distribution is 4.0(15) ps in the system of (19)Mg. The Q value of the 2p decay of the (19)Mg ground state inferred from the measured p-p-(17)Ne correlations is 0.75(5) MeV.

16.
J Chem Phys ; 127(4): 044702, 2007 Jul 28.
Article in English | MEDLINE | ID: mdl-17672712

ABSTRACT

We present a theoretical study of the electromagnetic contribution to surface-enhanced Raman scattering (SERS) from a Langmuir-Blodgett film close to a metal surface. This macroscopic dipolar model fully accounts for the Raman-shifted emission so that meaningful SERS (electromagnetic) enhancement factors that do not depend only on the local electromagnetic field enhancement at the pump frequency are defined. For a plane metal surface, analytical SERS enhancement factors that are consistent for all pump beam polarization and molecular orientation are obtained. In order to investigate SERS on complex nanostructured metal surfaces, we introduce this model into the formally exact, Green's theorem surface integral equation formulation of the scattered electromagnetic field. This formulation is thus employed to calculate numerically the near-field and far-field emissions at the Raman-shifted frequency for very rough, random nanostructured surfaces, with emphasis on the impact of collective processes for varying pump frequency and Raman shift. Our results reveal that the widely used |E|4 approximation tends to overestimate average SERS enhancement factors.

17.
Langmuir ; 23(9): 5210-5, 2007 Apr 24.
Article in English | MEDLINE | ID: mdl-17381143

ABSTRACT

In this work Ag nanoparticles (AgNP) with surface-enhanced Raman scattering (SERS) activity were prepared and immobilized by laser irradiation on a water/ solid interface where the aqueous phase contains the Ag+ cation and the solid surface is of hydrophilic nature (glass and cellulose). The so-prepared AgNP demonstrated a high SERS effectiveness in the detection of dispersed adsorbates such as the case of the anthraquinonic dye alizarin. The size and SERS effectiveness of AgNP increases with the irradiation time, the laser power, and the cation concentration. Laser-induced AgNP can be classified into two classes attending to the morphology: spherical and planar. The latter are formed after longer irradiation times, being more active regarding the SERS efficiency. Ag photoreduction can be employed for in situ detection of the dye alizarin, but when the dye is placed on a hydrophilic substrate. Even so, this in situ SERS technique could be attractive for analytical applications involving the in situ detection of the analyzed species, such as the case of dyes in artistical objects, textiles, foods, and surface analysis in general.


Subject(s)
Anthraquinones/chemistry , Lasers , Nanoparticles , Silver , Spectrum Analysis, Raman/methods , Molecular Structure , Nanoparticles/chemistry , Nanoparticles/radiation effects , Oxidation-Reduction , Particle Size , Photochemistry , Sensitivity and Specificity , Silver/chemistry , Silver/radiation effects , Surface Properties , Time Factors , Water/chemistry
18.
Nefrologia ; 26(2): 261-6, 2006.
Article in Spanish | MEDLINE | ID: mdl-16808265

ABSTRACT

INTRODUCTION: Lymphocytotoxic antibodies reduce the expectancy of renal transplantation due to the increased risk of a positive crossmatch. MATERIAL AND METHODS: We analyzed the evolution of eight kidney transplants performed in our unit in presence of a positive crossmatch with historical T and/or B lymphocyte positive crossmatches. RESULTS: Mean panel reactivity was 76,6 +/- 25,7% (r: 22-100%), been higher than 75% in six patients. Six patients were recipients of a second or third transplant. Immunosuppression consisted of quadruple therapy including induction with thymoglobuline. Five patients had delayed graft function, and one had primary non-function of the graft. One patient lost her graft due to chronic allograft nephropathy in the second year postransplantation. Six patients maintained a good renal function (serum creatinine 1,2 +/- 0,5 mg/dl, proteinuria 0,20 +/- 0,34 g/day). CONCLUSION: Renal transplantation in presence of a positive cross-match with historical serum and T lymphocytes and/or B lymphocytes, was followed by a satisfactory graft survival.


Subject(s)
Histocompatibility Testing , Kidney Transplantation/immunology , Adult , Aged , Female , Humans , Male , Middle Aged , Retrospective Studies
19.
Biopolymers ; 82(4): 405-9, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16421915

ABSTRACT

Surface-enhanced Raman spectroscopy and UV-vis absorption spectroscopy were employed to study the interaction between the red dye alizarin and ovalbumin (OA), to check the effect of binding media usually employed when applying this pigment in painting practices based on egg tempera. The protein/alizarin interaction is rather weak and takes place through the alizarin neutral form, which interacts with exposed hydrophobic moieties of OA. This effect is of great interest from an artistic point of view because the dye color can be modified. Furthermore, the interaction with alizarin could induce a change in the protein structure, leading to a denaturation and subsequent aggregation.


Subject(s)
Anthraquinones/chemistry , Ovalbumin/chemistry , Spectrum Analysis, Raman/methods , Microscopy, Electron, Scanning , Nanostructures/chemistry , Nanostructures/ultrastructure , Spectrophotometry, Ultraviolet/methods
20.
Appl Spectrosc ; 60(12): 1386-91, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17217587

ABSTRACT

The chemical degradation of curcumin (CU) in aqueous solution and on silver nanoparticles was studied by means of ultraviolet (UV)-visible absorption and surface-enhanced Raman (SERS) spectroscopy at different pH levels and upon light irradiation. CU undergoes a chemical degradation in aqueous solution mainly when the pH is increased. The CU degradation is catalytically enhanced in the presence of Ag nanoparticles. In general, CU degradation implies two steps: (1) the breakdown of the interring chain connecting the two CU aromatic side rings, producing smaller phenolic compounds rich in carboxylate groups, and (2) polymerization of the resulting phenolic products, giving rise to phenolic polymeric products. The degradation-polymerization mechanism can be modulated depending on the experimental conditions. The chemical photoproducts resulting from the visible light irradiation are similar to the polycatechol products obtained when catechol is adsorbed on Ag nanoparticles.

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