Single-Molecule Catalysis in the Palladium Cross-Coupling Reaction Cycle.

Single-molecule (SM) methods are applied to study various types of catalytic processes in chemical and biochemical reactions. In this study, the Suzuki-Miyaura cross-coupling reaction forming a fluorescent product is investigated within the SM approximation. Stochastic analysis of emission intermittency in selected nanoscopic spots allows us to determine the single-molecule turnover frequency (SM-TOF) of the Pd catalyst in a specific probe reaction.

Acid selenites as new selenium precursor for CdSe quantum dot synthesis.

Chemical precursors for nanomaterials synthesis have become essential to tune particle size, composition, morphology, and unique properties. New inexpensive precursors investigation that precisely controls these characteristics is highly relevant. We studied new Se precursors, the acid selenites (R-O-SeOOH), to synthesize CdSe quantum dots (QDs).

Fecal calprotectin levels in acute anterior uveitis in patients with spondyloarthritis.

Purpose: This study measured fecal calprotectin levels in a series of patients with anterior uveitis in order to determine whether anterior uveitis patients with associated spondyloarthritis have higher levels of fecal calprotectin than patients with anterior uveitis of other etiologies. A third group of patients with spondyloarthritis without uveitis was also evaluated to understand the role of acute anterior uveitis in increasing fecal calprotectin.

Methods: In this cross-sectional study, 28 patients were divided into three groups: (a) Group 1, spondyloarthritis and uveitis (n=9); (b) Group 2, spondyloarthritis without uveitis (n=10); and (c) Group 3, uveitis without spondyloarthritis (n=9).

Reactive Phenanthrene Derivatives as Markers of Amino Groups in Fluorescence Microscopy of Surface Modified Micro-Zeolite L.

Two reactive phenanthrene derivatives, 4-(1H phenanthrol [9,10-d] imidazole-2-yl) benzaldehyde (PIB) and 6,9-dimethoxyphenanthro[9,10-c]furan-1,3-dione (PA) with high fluorescent quantum yields were prepared and used as fluorescent marker in fluorescence microscopy. In particular, silane modified μmZeolite-L containing amino group (-NH) in the surface were labeled with the phenanthrene derivatives allowing good imaging resolution and spectroscopy measurements. The presence of a large Stokes shift of the probes due to their intramolecular charge-transfer character gives an advantage of the compounds in confocal laser fluorescence microscopy due to easy signal separation in excitation and emission wavelengths.

Dry eye and percentage of body fat: a cross-sectional prospective study.

Background: Dry eyes are common in the general population. Some studies associate high prevalence of dry eyes with lipid metabolic changes and body fat composition.

Aim: To study the association of dry eye with percentage of body fat.

Single-Molecule Observations Provide Mechanistic Insights into Bimolecular Knoevenagel Amino Catalysis.

While single-molecule (SM) methods have provided new insights to various catalytic processes, bimolecular reactions have been particularly challenging to study. Here, the fluorogenic Knoevenagel condensation of an aromatic aldehyde with methyl cyanoacetate promoted by surface-immobilized piperazine is quantitatively characterized using super-resolution fluorescence imaging and stochastic analysis using hidden Markov modeling (HMM). Notably, the SM results suggest that the reaction follows the iminium intermediate pathway before the formation of a fluorescent product with intramolecular charge-transfer character.

Dry eyes in patients with diabetes mellitus.

Dry eyes may be caused by impairment in the tear production or excessive tear evaporation and are associated with photophobia, red eyes, vision impairment, local pain and pruritus. It has been described that patients with Diabetes Mellitus (DM) may have a higher prevalence of dry eyes than normal population. This is a case control study of 120 patients with Diabetes Mellitus (DM) and 120 paired controls aiming to compare their prevalence of dry eyes (by the Schirmer test) and its severity (measured by OSDI or Ocular Surface Disease Index) as well as their association with diseases' clinical variables.

Highly fluorescent hybrid pigments from anthocyanin- and red wine pyranoanthocyanin-analogs adsorbed on sepiolite clay.

Flavylium cations serve as models for the chemical and photochemical reactivity of anthocyanins, the natural plant pigment responsible for many of the red, blue and purple colors of fruits and flowers. Likewise, pyranoflavylium cations serve as models of the fundamental chromophoric moiety of pyranoanthocyanins, molecules that can form from reactions of grape anthocyanins in red wines during their maturation. In the present work, hybrid pigments are prepared by the adsorption of a series of five synthetic flavylium cations (FL) and five synthetic pyranoflavylium cations (PFL) on sepiolite clay (SEP).

Styryl dye formation promoted by catalytic centers of piperazine bound to a silica surface traced by single molecule fluorescence microscopy.

The styryl dye (E)-2-[3-[4-(diphenylamine) phenyl]-1-(p-tolyl)-allylidene]-malononitrile (DFTAM) was prepared by Knoevenagel condensation using homogeneous and surface bound amino catalysts. The catalysis by surface bound piperazine allowed the study of the condensation reaction at a single molecule (SM) level using total internal fluorescence microscopy (TIRFM). The turnover rate of the surface catalyst is dependent on the presence of the byproduct water of the condensation reaction.

Aryl-Substituted Ruthenium(II) Complexes: A Strategy for Enhanced Photocleavage and Efficient DNA Binding.

Ruthenium polypyridine complexes have shown promise as agents for photodynamic therapy (PDT) and tools for molecular biology (chromophore-assisted light inactivation). To accomplish these tasks, it is important to have at least target selectivity and great reactive oxygen species (ROS) photogeneration: two properties that are not easily found in the same molecule. To prepare such new agents, we synthesized two new ruthenium complexes that combine an efficient DNA binding moiety (dppz ligand) together with naphthyl-modified (1) and anthracenyl-modified (2) bipyridine as a strong ROS generator bound to a ruthenium complex.

Methyltransferase-directed covalent coupling of fluorophores to DNA.

We report an assay for determining the number of fluorophores conjugated to single plasmid DNA molecules and apply this to compare the efficiency of fluorophore coupling strategies for covalent DNA labelling. We compare a copper-catalyzed azide-alkyne cycloaddition reaction, amine to -hydroxysuccinimidyl ester coupling reaction and strain-promoted azide-alkyne cycloaddition reaction for fluorescent DNA labelling. We found increased labelling efficiency going from the amine to -hydroxysuccinimidyl ester coupling reaction to the copper-catalyzed azide-alkyne cycloaddition and found the highest degree of DNA labelling with the strain-promoted azide-alkyne cycloaddition reaction.

Imaging the photoinduced charge injection in CdS/TiO nanoparticles by the sequential fluorescence mapping method.

The combination of a sensitizer and TiO nanoparticles forming a photocatalytic material is a central issue in many fields of applied photochemistry. The charge injection of emissive sensitizers into the conduction band of the semiconductor TiO may form a photoactive region that becomes dark, or it has a very low emission signal due to the generation of sensitizer radicals. However, by sequential coupling of a selected photoredox dye, such as resazurin, the dark region may become fluorescent at the interfaces where the charge injection has taken place due to the concomitant formation of fluorescent resorufin by cascade electron transfer.

The spatial distribution of the photostability of thionine in zeolite L nanochannels investigated by Photobleaching Lifetime Imaging Microscopy.

Dye photobleaching is a photochemical reaction that can be investigated locally using fluorescence microscopy techniques. In this study, a user-friendly computational tool to assist photobleaching experiments called Photobleaching Lifetime Imaging Microscopy (PbLIM) is presented. With this tool it is possible to recover the photobleaching kinetics spatially, where a photobleaching lifetime is generated for each pixel of the image.

Fluorescence from bisaryl-substituted maleimide derivatives.

A series of bisaryl-substituted fluorescent maleimides was synthesized via the Heck arylation. The compounds showed broad fluorescence emission bands in the visible region, a large Stokes shift in polar solvents and emission quantum yields varying from 0.04 to 0.

Fluorescence spectroscopy and confocal microscopy of the mycotoxin citrinin in condensed phase and hydrogel films.

The emission spectra, quantum yields and fluorescence lifetimes of citrinin in organic solvents and hydrogel films have been determined. Citrinin shows complex fluorescence decays due to the presence of two tautomers in solution and interconversion from excited-state double proton transfer (ESDPT) process. The fluorescence decay times associated with the two tautomers have values near 1 and 5 ns depending on the medium.

Demographic, clinical, laboratory and treatment characteristics of spondyloarthritis patients with and without acute anterior uveitis.

Context And Objective: Acute anterior uveitis is a common extra-articular manifestation in spondyloarthritis patients. The aim of this study was to compare demographic, clinical, laboratory and treatment data among spondyloarthritis patients with and without acute anterior uveitis.

Design And Setting: This was a cross-sectional analytical study at the Rheumatology Outpatient Clinic of the Evangelical University Hospital, Curitiba, Brazil.

[Lacrimal dysfunction and pregnancy].

Purpose: To assess the prevalence of lacrimal dysfunction during pregnancy comparing it to non-pregnant women and to correlate these findings with obstetric history.

Methods: We interviewed 150 pregnant and 150 non-pregnant women for symptoms of dry eyes and obstetric history. Both groups underwent Schirmer I testing and responded to a questionnaire on dry eye symptoms.

[Translation and validation of ocular surface disease index to Portuguese].

Purpose: To develop a cross-cultural Ocular Surface Disease Index (OSDI) for the Brazilian population and analyze its validity and effectiveness.

Methods: Based on the guidelines of Guillemin et al., four English teachers, an ophthalmologist, a rheumatologist, two ophthalmology residents and a native American who does not speak Portuguese were invited.

[Anterior uveitis in the absence of scleritis in a patient with rheumatoid arthritis: case report].

Rheumatoid arthritis is the most common collagenosis and affects almost 0.6% of Brazilian population. It is an important cause of articular deformities.

Secondary Sjögren's syndrome and disease activity of rheumatoid arthritis.

Objective: To study the relationship of the presence of secondary SS with disease activity, duration in RA.

Methods: Eighty two patients with RA were submitted to Schirmer test, minor salivary gland biopsy, questionnaire on sicca symptoms, DAS-28 4v determination.

Results: In this population, 20 (24.

Intrachain energy migration to weak charge-transfer state in polyfluorene end-capped with naphthalimide derivative.

Polyfluorene end-capped with N-(2-benzothiazole)-1,8-naphthalimide (PF-BNI) is a highly fluorescent material with fluorescence emission modulated by solvent polarity. Its low energy excited state is assigned as a mixed configuration state between the singlet S(1) of the fluorene backbone (F) with the charge transfer (CT) of the end group BNI. The triexponential fluorescence decays of PF-BNI were associated with fast energy migration to form an intrachain charge-transfer (ICCT) state, polyfluorene backbone decay, and ICCT deactivation.

[Analysis of 29 cases of scleritis. Experience of a Rheumato-Ophthalmology Service].

Unlabelled: Scleritis are entities that may have rheumatic diseases, infections or tumors as etiologic factors or may be a disease restricted only to the eye.

Purpose: To share a three year experience of a rheumato-ophthalmologic ambulatory in the diagnosis and treatment of patients with scleritis.

Methods: This was a study of 29 cases.

Excited-state dynamics of polyfluorene derivatives in solution.

The excited-state dynamics of two polyfluorene copolymers, one fully conjugated containing phenylene vinylene units alternated with 9,9'-dihexylfluorenyl groups and the other segmented by -(CH2)8- spacer, were studied in dilute solution of different solvents using a picosecond single-photon timing technique. The excited-state dynamics of the segmented copolymer follows the Förster resonant energy-transfer model which describes intrachain energy-transfer kinetics among random oriented chromophores. Energy transfer is confirmed by analysis of fluorescence anisotropy relaxation with the measurement of a short decay component of about 60 ps.

Static and dynamic bimolecular fluorescence quenching of porphyrin dendrimers in solution.

The fluorescence quenching kinetics of two porphyrin dendrimer series (GnTPPH(2) and GnPZn) by different type of quenchers is reported. The microenvironment surrounding the core in GnPZn was probing by core-quencher interactions using benzimidazole. The dependence of quencher binding constant (K ( a )) on generation indicates the presence of a weak interaction between branches and the core of the porphyrin dendrimer.