105,884 research outputs found
Reconstituted CP29 : multicomponent fluorescence decay from an optically homogeneous sample
No full textThe multiexponential fluorescence decay of the CP29 complex in which the apoprotein and pigments were reconstituted in vitro was examined. Of the three decay components observed only the two dominant ones, with about 3 and 5 ns lifetimes, were studied. The main question addressed was whether the multicomponent decay was associated with sample optical heterogeneity. To this end, we examined the optical absorption and fluorescence of the CP29 sample by means of two different and independent experimental strategies. This approach was used as the wavelength positions of the absorption/fluorescence spectral forms has recently been shown to be a sensitive indicator of the binding site-induced porphyrin ring deformation (Zucchelli et al. Biophys J 93:2240-2254, 2007) and hence of apoprotein conformational changes. The data indicate that this CP29 sample is optically homogeneous. It is hypothesised that the different lifetimes are explained in terms of multiple detergent/CP29 interactions leading to different quenching states, a suggestion that allows for optical homogeneity
Delamination localisation and length estimation in composite laminate beam by VSHM and pattern recognition methods
No full textThe focus of this work is to investigate the delamination damage in laminate composite beams, to fix a Vibration-based structural health monitoring (VSHM) method for the laminate structures. The analysis is concentrated on the vibration characteristics of the samples and, in particular, the attention is addressed on the first several natural frequencies of a composite laminate beam with a delamination damage. The core of this work is an experimental investigation on the vibration response of a composite laminate beam and its changes caused by delaminations with different sizes and in different locations of the beam. The study is divided in 3 sections: delamination detection, delamination localization, and delamination estimate. The aim is to determine how the first six harmonics frequencies change due to the delamination, and the results show that they can be successfully used to investigate the presence, the location and the dimensions of the delamination in a composite beam. A Pattern Recognition analysis is used to locate the damage, while the detection and the evaluation are done using the changes in the harmonic frequencies. A finite element analysis is performed, and the variations of the natural frequencies due to delamination are in good agreement with the experimental results
Photoinhibition in vivo and in vitro involves weakly coupled chlorophyll-protein complexes
No full textIn the present study the analysis of the relation between the excited state population in the photosystem 11 (PSII) antenna and photoinactivation has been extended from an in vitro system, isolated thylakoids, to an in vivo system, Chlamydomonas reinhardtii cells. The results indicate that the excited state quenching by an added singlet quencher induces maximal protection against photoinhibition of about 30% of that expected on the basis of the observed light intensity-treatment time reciprocity rule. Similar results, obtained previously with thylakoids, have been interpreted in terms of damaged or incorrectly assembled complexes that play an important role in photoinhibition in the thylakoid membranes (Santabarbara, S., K. Neverov, F. M. Garlaschi, G. Zucchelli and R. C. Jennings [2001] Involvement of uncoupled antenna chlorophylls in photoinhibition in thylakoids. FEBS Lett. 491, 109-113.). In an attempt to better define this aspect, the photoinhibition action spectra were determined for mutant barley thylakoids, lacking the chlorophyll (Chl) a-b complexes of the outer antenna, and for its wild type. The results indicate that in both systems the action spectra are significantly blueshifted (2-4 nm) and are broader than the PSII absorption in the membranes. These data are interpreted in terms of a heterogeneous population of outer and inner antenna pigment-protein complexes that contain significant levels of uncoupled Chl
Coronally advanced flap: a modified surgical approach for isolated recession-type defects: three-year results.
No full textVarious modifications of the coronally displaced flap have been proposed in the literature with the attempt of treating gingival recession with uneven predictable results. The goal of the present study was to evaluate the effectiveness with respect to root coverage of a modification of the coronally advanced flap procedure for the treatment of isolated recession-type defects in the upper jaw. Methods: Forty isolated gingival recessions with at least 1 mm of keratinized tissue apical to the defects were treated with a modified approach to the coronally advanced flap. The main change in the surgical procedure consisted in the modification of flap thickness and dimension of surgical papillae during flap elevation. All recessions fall into Miller class I or II. The clinical re-evaluation was performed 1 year and 3 years after the surgery. Results: At the 1-year examination, the average root coverage was 3.72 ± 1.0 mm (98.6% of the pre-operative recession depth) and 3.64 ± 1.1 mm (96.7%) at 3 years. The gain in probing attachment amounted to 3.65 ± 1.10 mm at 1 year and to 3.70 ± 1.09 mm at 3 years. The average increase of keratinized tissue between the baseline and the 3-year follow-up amounted to 1.78 ± 0.90 mm. All changes of keratinized tissue (difference between baseline and 1 year, baseline and 3 years, and between 1 and 3 years) were statistically significant. Conclusion: The modified coronally advanced surgical technique is effective in the treatment of isolated gingival recession in the upper ja
Ergodicity, configurational entropy and free energy in pigment solutions and plant photosystems : influence of excited state lifetime
No full textWe examine ergodicity and configurational entropy for a dilute pigment solution and for a suspension of plant photosystem particles in which both ground and excited state pigments are present. It is concluded that the pigment solution, due to the extreme brevity of the excited state lifetime, is non-ergodic and the configurational entropy approaches zero. Conversely, due to the rapid energy transfer among pigments, each photosystem is ergodic and the configurational entropy is positive. This decreases the free energy of the single photosystem pigment array by a small amount. On the other hand, the suspension of photosystems is non-ergodic and the configurational entropy approaches zero. The overall configurational entropy which, in principle, includes contributions from both the single excited photosystems and the suspension which contains excited photosystems, also approaches zero. Thus the configurational entropy upon photon absorption by either a pigment solution or a suspension of photosystem particles is approximately zero
Antenna entropy in plant photosystems does not reduce the free energy for primary charge separation
No full textWe have investigated the concept of the so-called "antenna entropy" of higher plant photosystems. Several interesting points emerge:
1. In the case of a photosystem which harbours an excited state, the "antenna entropy" is equivalent to the configurational (mixing) entropy of a thermodynamic canonical ensemble. The energy associated with this parameter has been calculated for a hypothetical isoenergetic photosystem, photosystem I and photosystem II, and comes out in the range of 3.5 - 8% of the photon energy considering 680 nm.
2. The "antenna entropy" seems to be a rather unique thermodynamic phenomenon, in as much as it does not modify the free energy available for primary photochemistry, as has been previously suggested.
3. It is underlined that this configurational (mixing) entropy, unlike heat dispersal in a thermal system, does not involve energy dilution. This points out an important difference between thermal and electronic energy dispersal
A novel biopsy technique for lesions involvinginterproximal soft tissues
No full textBackground: Biopsy of soft tissues around teeth can cause periodontal deficiency with several side effects. When the neoformation involves frontal areas biopsy often induces an aesthetic impairment, particularly critical when the interdental papilla is entailed. Description of the procedure: A new surgical approach to treat lesions involving interdental tissues is described. The flap design is characterized by a sub-marginal scalloped incision, possibly confined into the keratinized tissue at the vestibular side. The incision starts 1 mm above the lesion, in the midline between the two confining teeth. With a parabolic shape, the incision reaches the gingival margin at the distal line angle of the distal tooth. Hence, another parabolic incision is performed connecting the starting point with the marginal mesial line angle of the mesial tooth. After this step, two options are applied depending on the lesion extension. When the lesion is confined coronally to the line connecting the gingival margin zeniths of the two adjacent teeth, oblique linear incisions are performed till to the gingival margin zeniths. Otherwise, when the lesion extends beyond this line, two parabolic incisions are per-formed on both adjacent teeth, till to the distal and mesial line angle respectively. Specific anatomic measurements rule up the incisional design. For the palatal/lingual side, the incision follows the principles of a general excisional procedure. Intrasulcular incisions are then made and the lesion with surrounding tissues are collected for examination. Both full-thickness and split-thickness are used for the buccal flap elevation. De-epithelized the adjacent anatomic papillae, two sling sutures are used to stabilize the entire flap to the most feasible coronal position. Generally single sutures are used for the palatal side and the eventual graft. Outcomes: All 9 cases treated so far have ever shown an esthetically satisfying outcome without recurrence or adverse events. Conclusions: This technique allows clinician to restore gingival health preserving aesthetics and function
Why is there a lack of evidence regarding errors and complications in periodontal and implant therapy?
No full textThe occurrence of errors, complications, and adverse effects may occur as a consequence of single or multiple events related to the clinician and/or patient. Apparently, the amount of dental literature on these undesirable outcomes has not been as prolific as that obtained for conventional primary periodontal outcome measures. This review explores the potential reasons for the lack of studies reporting on errors and complications in periodontal and implant therapy, as well as other noteworthy methodological aspects, to enlighten their impact on the selection of the best (or most appropriate) “gold standard” periodontal/implant-related treatment options, and on the overall decision-making process. The following points were addressed: (a) the importance of reporting errors and complications in clinical research; (b) the adequate reporting of errors and complications in periodontology and dental implantology; and (c) efficacy trials vs effectiveness studies and their impact on the assessment and report of periodontal and implant treatment-related risks and complications
Ionospheric Observatory Development At Mario Zucchelli Station
No full textSince 1995 Italian Ionospheric Antarctic Observatory at Terra Nova Bay, now “MARIO ZUCCHELLI”, station (geographic coordinates: 74.70°S, 164.11°E) performs continuous and systematic ionospheric vertical soundings. Long time series of continuous and accurate ionospheric observations (more than one solar cycle) are necessary for a deeper understanding of the complex phenomena occurring in the upper atmosphere at high latitude; furthermore high rate soundings (at least four soundings per hour or more) contribute to the short-time prediction of the radiopropagation conditions and to the Space Weather.
During 2003–2004 Antarctic campaign a new digital ionosonde, recently developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome, (Italy), has been installed the Ionospheric Observatory and preliminary tests have been carried out. This new Advanced Ionospheric Sounder-INGV, briefly AIS, is integrated in a stand alone system during winter time: the sounding, device settings and data sending to Rome are completely automatic and remote programmable. Ionograms are available on line at the INGV web and ftp server.
The new features of the Ionospheric Observatory are presented and preliminary statistics on the reliability and validation of the experimental observation are shown and discussed.Published1.7. Osservazioni di alta e media atmosfera3.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeope
- …
