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Peer Reviewed
See detailThe photochemistry of the semi-oxidized form of Eosin Y and Rose Bengal in aqueous sodium dodecyl sulphate solutions
Seret, Alain ULg; Van de Vorst, Albert

in Journal of Photochemistry and Photobiology A : Chemistry (1988), 43(2), 193-206

In aerobic aqueous solutions, the semi-oxidized form of the halofluorescein dyes disappears via a bimolecular reaction with itself and via the formation of an adduct with OH− ions. In aerobic aqueous ... [more ▼]

In aerobic aqueous solutions, the semi-oxidized form of the halofluorescein dyes disappears via a bimolecular reaction with itself and via the formation of an adduct with OH− ions. In aerobic aqueous solutions of sodium dodecylsulphate, semi-oxidized rose bengal is solubilized in the micelles, and its exit rate from the micellar aggregates is lower than 60 s−1. The properties of semi-oxidized eosin Y in sodium dodecylsulphate solutions are interpreted in terms of a model based on an adsorption equilibrium between water-bound and micelle-bound dye radicals. This equilibrium depends on the surfactant concentration between the critical micelle concentration and 80 mmol dm−3. Over this range, the reactivity of the semi-oxidized form with itself and towards hydrophilic quenchers decreases when the surfactant concentration is increased. The reaction of the semi-oxidized form with itself is involved in the bleaching of these dyes and the photoproduct is clearly able to react with the semi-oxidized radical of the xanthene dyes. [less ▲]

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See detailPhotoclick chemistry: Applications to 18F radiotracers preparation
Thonon, David ULg; Goukens, Eve ULg; Kaisin, Geoffroy ULg et al

in Journal of Labelled Compounds and Radiopharmaceuticals (2011)

Detailed reference viewed: 61 (21 ULg)
Peer Reviewed
See detailPhotodegradation of bacteria on TiO2 thin films produced by sol-gel method
Tasseroul, Ludivine ULg; Braconnier, Benoît; Nonet, Stéphane et al

Conference (2008)

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See detailPhotodegradation of bacteria with TiO2 produced by sol-gel method
Tasseroul, Ludivine ULg; Pàez Martinez, Carlos ULg; Braconnier, Benoît et al

Poster (2007)

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See detailPhotodegradation of phenol and benzoic acid by sol-gel-synthesized alkali metal-doped ZnO
Benhebal, H.; Chaib, M.; Léonard, Angélique ULg et al

in Materials Science in Semiconductor Processing (2012), 15(3), 264269

Detailed reference viewed: 40 (7 ULg)
See detailPhotodetachment and Photodissociation Mass Spectrometry of Biomolecule Ions
Gabelica, Valérie ULg

Conference (2007, April 27)

We recently explored the effects of irradiating DNA polyanions stored in a quadrupole ion trap (QIT) mass spectrometer with an optical parametric oscillator (OPO) laser between 250 nm and 285 nm. We ... [more ▼]

We recently explored the effects of irradiating DNA polyanions stored in a quadrupole ion trap (QIT) mass spectrometer with an optical parametric oscillator (OPO) laser between 250 nm and 285 nm. We studied DNA 6-mer to 20-mer single strands, and 12-base pair double strands. In all cases, laser irradiation causes electron detachment from the multiply charged DNA anions. Electron photo-detachment efficiency directly depends on the number of guanines in the strand, and maximum efficiency is observed between 260 and 275 nm. Collisional activation of the radical anions results in extensive fragmentation, which can be used to sequence the DNA strands. It has therefore important potential applications in analytical chemistry. We also obtained preliminary results on laser irradiation of DNA coupled to other chromophores (covalently bound or noncovalently bound). Depending on the chromophore, three different behaviors are encountered: (1) the photon energy can be redistributed in the molecule by internal conversion, (2) electron photodetachment was observed for a few chromophores, and (3) specific photodissociation was observed for a porphyrin chromophore. Here we will address the question of the mechanism of electron photodetachment. DNA multiply charged anions undergo one-photon electron ejection (oxidation) when subjected to laser irradiation at 260 nm (4.77 eV). Electron photodetachment is likely a fast process, given that photodetachment is able to compete with internal conversion and/or radiative relaxation to the ground state. The DNA [6-mer]3- ions studied here show a marked sequence-dependence of electron photodetachment yield. Remarkably, the photodetachment yield (dG6 > dA6 > dC6 > dT6) is inversely correlated with the base ionization potentials (G < A < C < T). Sequences with guanine runs show increased photodetachment yield as the number of guanine increases, in line with the fact that positive holes are the most stable in guanine runs. This correlation between photodetachment yield and the stability of the base radical may be explained by tunneling of the electron through the repulsive Coulomb barrier. The wavelength-dependence of electron detachment yield was studied for dG63-. Maximum electron photodetachment is observed in the wavelength range corresponding to base absorption (260-270 nm). This demonstrates the feasibility of gas-phase UV spectroscopy on large DNA anions. The calculations and the wavelength dependence suggest that the electron photodetachment is initiated at the bases and not at the phosphates. This also indicates that, although direct photodetachment could also occur, autodetachment from excited states, presumably corresponding to base excitation, is the dominant process at 260 nm. Excited states dynamics of large DNA strands still remains largely unexplored, and photo-oxidation studies on trapped DNA multiply charged anions can help bridging the gap between gas-phase studies on isolated bases or base pairs and solution-phase studies on full DNA strands. Time-resolved measurements on photodetachment and photodissociation can be used to contribute elucidating the mechanisms at stake in these novel experiments. [less ▲]

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See detailPhotodetachment and photodissociation mass spectrometry of DNA multiply charged ions
Gabelica, Valérie ULg; Rosu, Frédéric ULg; De Pauw, Edwin ULg et al

in Beck, Rainer D.; Drabbels, Marcel; Rizzo, Thomas R. (Eds.) Contributions 16th Symposium on Atomic and Surface Physics and Related Topics (2008)

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See detailPhotodetection Signals for Controlling Combustion
Parada, Luis; Ngendakumana, Philippe ULg

Report (2006)

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See detailA Photodiode for Combustion Control (1)
Tartari, Paula; Ngendakumana, Philippe ULg

Report (2003)

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See detailPhotodiodes for Combustion Control (V2)
Tartari, Paula; Ngendakumana, Philippe ULg

Report (2003)

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See detailPhotodissociation and radiative association ofHeH+ in the metastable triplet state
Loreau, Jerôme; Vranckx, Stéphane; Desouter-Lecomte, Michèle ULg et al

in Journal of Physical Chemistry A (2013), 117

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See detailPhotodissociation of the HeH+ ion into excited fragments (n=2,3) by time-dependent methods
Sodoga, K.; Loreau, J.; Lauvergnat, D. et al

in Physical Review. A (2009), 2009(80), 033417

Detailed reference viewed: 14 (3 ULg)
See detailPhotodissociation spectroscopy of cationic porphyrins in the gas phase. Influence of the complexation with DNA. Comparison with solution phase
Rosu, Frédéric ULg; De Pauw, Edwin ULg; Gabelica, Valérie ULg et al

in Beck, Rainer D.; Drabbels, Marcel; Rizzo, Thomas R. (Eds.) Contributions 16th Symposium on Atomic and Surface Physics and Related Topics (2008)

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See detailPhotodynamic therapy and imiquimod immunotherapy for basal cell carcinomas
Nikkels, Arjen ULg; Pierard-Franchimont, Claudine ULg; Tassoudji, Nazli ULg et al

in Acta Clinica Belgica (2005), 60(5, Sep-Oct), 227-234

Photodynamic therapy (PDT) and topical imiquimod immunotherapy (TII) are two recently introduced treatment modalities for certain types of basal cell carcinomas (BCC). We present a review of the relevant ... [more ▼]

Photodynamic therapy (PDT) and topical imiquimod immunotherapy (TII) are two recently introduced treatment modalities for certain types of basal cell carcinomas (BCC). We present a review of the relevant literature and report our own findings regarding the efficacy and tolerance of PDT and TII in the treatment of BCCs. According to published studies, the cure rates range from 75-95% for PDT and 42-100% for TII, depending on treatment modalities and BCC type. In our observations, 13 patients with nodular or superficial BCCs were treated by PDT using two courses of 3-hour topical application of methyl aminolevulinate, followed by 8 minutes illumination (lambda = 634 rim, e = 37J/cm(2)). Biopsies were taken before and one month after PDT. Side effects including pain and crusting were assessed. Eight patients with superficial BCC were treated by TII using 3 monthly courses each consisting of 3 weekly applications for 3 weeks followed by one week out of treatment. Biopsies were taken before and after 3 months of TII. Adverse reactions including erythema, oozing, ulceration, and crusting were recorded. Clinico-histological cure was obtained in 12/13 PDT cases as assessed after I month, and in 6/8 TII cases after 3 months. Minimal pain during illumination and crust formation were observed in 7/13 and 3/13 PDT cases, respectively. Variable erythema, oozing, ulceration, and crusting were observed in all TII-treated lesions. It is concluded that PDT represents an active and well tolerated alternative treatment for both nodular and superficial BCCs. TII also shows activity, although the tolerance may be poor and cure needs a longer time to be obtained. The final cosmetic appearance was fine following both PDT and TII procedures. Both PDT and TII may leave intact neoplastic aggregates inside the skin. They cannot be clinically perceived, leading to unexpected recurrences. It is stressed that the currently available efficacy information about PDT and TII deals with short term follow-up periods. A 5-year follow-up must be awaited before drawing firm conclusions. [less ▲]

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See detailPhotodynamic therapy for cutaneous carcinoma
NIKKELS, Arjen ULg; thirion, L.; QUATRESOOZ, Pascale ULg et al

Poster (2007)

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See detailPHOTODYNAMIC THERAPY FOR MULTI-RESISTANT CUTANEOUS LANGERHANS CELL HISTIOCYTOSIS
FAILLA, Valérie ULg; WAUTERS, Odile ULg; CAUCANAS, MARIE et al

in Rare Tumors (2010), 2:e34

Langerhans cell histiocytosis is a rare group of proliferative disorders. Beside cutaneous involvement, other internal organs ca be affected. The treatment of cutaneous lesions is difficult and relies on ... [more ▼]

Langerhans cell histiocytosis is a rare group of proliferative disorders. Beside cutaneous involvement, other internal organs ca be affected. The treatment of cutaneous lesions is difficult and relies on topical corticosteroids, carmustine, nitrogen mustard, and photochemotherapy. Systemic steroids and vinblastine are used for recalcitrant skin lesions. Howerver, some cases fail to respond. An 18-month old boy presented a CD1a+, S100a+ Langerhans cell histocytosis with cutaneous and severe scalp involvement. Topical corticosteroids and nitrogen mustard failed to improve the skin lesions. Systemic corticosteroids and vinblastine improved the truncal involvement but had no effect on the scalp lesions. Methylaminolevulinate (MAL) based photodynamic therapy (PDT) resulted in a significant regression of the scalp lesions. Control histology revealed an almost complete clearance of the tumor infiltrate. Clinical follow-up after six months showed no recurrence. Although spontaneous regression of cutaneous Langerhans cell histiocytosis is observed, the rapid effect of photodynamic therapy for refractory skin lesions. Larger series are needed to determine whether photodynamic therapy deserves a place in the treatment of multiresistant cutaneous Langerhans cell histiocytosis. [less ▲]

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See detailPhotodynamic therapy of cancer: an update.
Agostinis, Patrizia; Berg, Kristian; Cengel, Keith A et al

in CA : A Cancer Journal for Clinicians (2011), 61(4), 250-81

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure that can exert a selective cytotoxic activity toward malignant cells. The procedure involves administration of ... [more ▼]

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure that can exert a selective cytotoxic activity toward malignant cells. The procedure involves administration of a photosensitizing agent followed by irradiation at a wavelength corresponding to an absorbance band of the sensitizer. In the presence of oxygen, a series of events lead to direct tumor cell death, damage to the microvasculature, and induction of a local inflammatory reaction. Clinical studies revealed that PDT can be curative, particularly in early stage tumors. It can prolong survival in patients with inoperable cancers and significantly improve quality of life. Minimal normal tissue toxicity, negligible systemic effects, greatly reduced long-term morbidity, lack of intrinsic or acquired resistance mechanisms, and excellent cosmetic as well as organ function-sparing effects of this treatment make it a valuable therapeutic option for combination treatments. With a number of recent technological improvements, PDT has the potential to become integrated into the mainstream of cancer treatment. [less ▲]

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See detailPhotodynamic therapy using methyl aminolevulinate in the management of primary superficial basal cell carcinoma: Clinical an health economic outcomes
Caekelbergh, K.; Nikkels, Arjen ULg; Leroy, B. et al

in Journal of Drugs in Dermatology (2009)

Background: Basal cell carcinoma (BBC) is the most common form of skin cancer worldwide. Different treatment options exist. The efficacy of photodynamic therapy with methyl aminolevulinate (MAL-PDT) has ... [more ▼]

Background: Basal cell carcinoma (BBC) is the most common form of skin cancer worldwide. Different treatment options exist. The efficacy of photodynamic therapy with methyl aminolevulinate (MAL-PDT) has been established in several randomized controlled trials (RCTs). Real life data can differ greatly from data derived from randomized controlled trials (RCTs). Objectives: To describe the results of a Belgian observational study concerning superficial BCC (sBCC) vis-à-vis clinical and health economic outcomes in order to evaluate the real-life practice of MAL-PDT. Methods: This study was a prospective, single-arm, open study conducted at eight dermatological institutions during six months after the first MAL-PDT treatment. Eligible patients had to present with lesions, suitable for MAL-PDT according to Belgian reimbursement criteria. Resource use was collected during the study period. Clinical Response (CR) and Cosmetic Outcome (CO), as well as cost of care were evaluated. A subset analysis of patients with sBCC only was conducted. Results: Ninety patients were identified for the analysis (mean age 65 years; 61 % female). The mean number of lesions per patient was 1.6, mostly located on the face, the back and the chest. For the entire period, the mean number of visits to a dermatologist was 4 per patient including two MAL-PDT sessions. The average, cumulative amount of MAL used per treatment was 1,256 mg. Two patients experienced adverse events at the application site, none of them serious, all resolved completely. The CR rate was 89 % at the end of the study. The CO was “excellent” or “good” in 96 % of the patients. Total cost of care was €289 ($ 414 U.S.) per patient. Cost per lesion was €195 ($ 280 U.S.). Conclusion: The result from the real-life practice study confirm the efficacy found in prior, prospective randomized trials. About four visits and less than one tube of MAL are needed for the full treatment of sBCC in one patient. [less ▲]

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See detailPhotoelastic effects in Single-Mode Optical Fibers
Roose, Stéphane ULg; Bastiaensens, Jan

Scientific conference (1987, June 04)

Detailed reference viewed: 3 (0 ULg)