Whole apple fruit (Malus domestica Borkh.) widely differing in pigment content and composition has been examined by recording its chlorophyll fluorescence excitation and diffuse reflection spectra in the visible and near UV regions. Spectral bands sensitive to the pigment concentration have been identified, and linear models for non-destructive assessment of anthocyanins, carotenoids, and flavonols via chlorophyll fluorescence measurements are put forward. The adaptation of apple fruit to high light stress involves accumulation of these protective pigments, which absorb solar radiation in broad spectral ranges extending from UV to the green and, in anthocyanin-containing cultivars, to the red regions of the spectrum. In ripening apples the protective effect in the blue region could be attributed to extrathylakoid carotenoids. A simple model, which allows the simulation of chlorophyll fluorescence excitation spectra in the visible range and a quantitative evaluation of competitive absorption by anthocyanins, carotenoids, and flavonols, is described. Evidence is presented to support the view that anthocyanins, carotenoids, and flavonols play, in fruit with low-to-moderate pigment content, the role of internal traps (insofar as they compete with chlorophylls for the absorption of incident light in specific spectral bands), affecting thereby the shape of the chlorophyll fluorescence excitation spectrum.

Currently there are limitations to gelation strategies to form ionically crosslinked hydrogels, derived in particular from a lack of control over the kinetics of release of crosslinking ions, which severely restrict applications. To address this challenge, we describe a new approach to form hydrogels of ionotropic polymers using competitive displacement of chelated ions, thus making specific ions available to induce interactions between polymer chains and form a hydrogel. This strategy enables control of ion release kinetics within an aqueous polymer solution and thus control over gelation kinetics across a wide range of pH. The described technique simplifies or facilitates the use of ionotropic hydrogels in a range of applications, such as 3D printing, microfluidic-based cell encapsulation, injectable preparations and large scale bubble and solid free mouldable gels. We investigate a range of chelatorion combinations and demonstrate this powerful method to form hydrogels across a wide range of pH and µm -cm length scales. We highlight our findings by applying this gelation strategy to some of the more challenging hydrogel application areas using alginate and polygalacturonate as model polymer systems.

Fluorescence studies were performed on the extrusions from pilosebaceous follicles. Pressure extractions produced follicle samples which showed fluorescence under Wood's light. The samples were then analysed in a fluorometer giving corrected excitation spectra. The structured emission spectra achieved were interpreted as being due to porphyrins produced by Propionibacterium acnes (P. acnes). Details in the spectra showed close resemblance to spectra from cultured P. acnes cells. The emission spectra showed distinct features in all the four subjects investigated (who were different with respect to age, sex, follicle sampling area, and tendency to acne) and dominant peaks due to at least three porphyrins were found. The concentrations of these porphyrins vary from case to case. Excitation spectra were recorded and supported the assumption that the fluorescent emission was partly due to coproporphyrins and metalloporphyrins in the samples. Free protoporphyrins did not seem to be present in the extrusions. The excitation spectra, in particular, vary from person to person but seem to be constant over time in one and the same subject.

Plants are commonly subjected to several environmental stresses that lead to an overproduction of reactive oxygen species (ROS). As plants accumulate proline in response to stress conditions, some authors have proposed that proline could act as a non-enzymatic antioxidant against ROS. One type of ROS aimed to be quenched by proline is singlet oxygen (1O2)-molecular oxygen in its lowest energy electronically excited state-constitutively generated in oxygenic, photosynthetic organisms. In this study we clearly prove that proline cannot quench 1O2 in aqueous buffer, giving rise to a rethinking about the antioxidant role of proline against 1O2. Highlights Pro was proposed to be a quencher of 1 O 2 , but a direct prove is still remaining  19 Abstract 20Plants are commonly subjected to several environmental stresses that lead to an overproduction of reactive 21 oxygen species (ROS). As plants accumulate proline in response to stress conditions, some authors have 22proposed that proline could act as a non-enzymatic antioxidant against ROS. One type of ROS aimed to be 23 quenched by proline is singlet oxygen ( 1 O 2 )-molecular oxygen in its lowest energy electronically excited 24 state-constitutively generated in oxygenic, photosynthetic organisms. In this study we clearly prove that proline 25 cannot quench 1 O 2 in aqueous buffer, giving rise to a rethinking about the antioxidant role of proline against 1 O 2 .

The photophysical properties of a series of platinum(II) acetylide compounds (trans-Pt(PBu(3))(2)(C[triple bond]C-R)(2)) with the R group consisting of two or three aryl rings (phenyl, phenyl/thiophenyl, phenyl/triazolyl) linked together with ethynyl groups were systematically investigated. Four new structurally similar compounds are reported with: (i) a bithiophene unit in the ligands, (ii) methyl or (iii) methoxy substituents on the aryl ring ligands that promote a more twisted conformation along the long axis of the molecule, and (iv) with two different alkynylaryl ligands giving rise to an asymmetric substitution with respect to the photoactive metal ion center. The spectroscopic studies include optical absorption, spectrally and time-resolved luminescence, as well as transient absorption spectra. The ground-state UV absorption between 300 and 420 nm gave rise to fluorescence with quantum efficiencies in the range of 0.1-1% and efficient intersystem crossing to triplet states. Phosphorescence decay times were in the order of 10-500 micros in oxygen-evacuated samples. The triplet states also lead to strong broadband triplet-triplet absorption between 400 and 800 nm. The complex with asymmetric substitution was found to populate two triplet states of different structure and energy.