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Raffaele Nuzzi,1 Claudio Burato,1 Federico Tridico,1 Alessia Nuzzi,2 Paolo Caselgrandi1 1Eye Clinic Section, Department of Surgical Sciences, University of Turin, Turin, Italy; 2Department of Clinical Sciences and Community Health, Eye Clinic San Giuseppe Hospital, IRCCS Multimedica, University of Milan, Milan, ItalyCorrespondence: Raffaele Nuzzi, Eye Clinic Section, Department of Surgical Sciences, University of Turin, Turin, Italy, Email prof.nuzzi_raffaele@hotmail.itBackground: The purpose of this prospective study is to evaluate the effects of different suturing techniques in perforating keratoplasty surgery, in order to identify the most effective in reducing post-operative astigmatism.Methods: We analysed data from patients who underwent penetrating keratoplasty for different indications. All interventions were performed by the same surgeon. Patients were subjected to a follow-up of at least 12 months after surgery, during which astigmatism (assessed by keratometry, topography and refraction) best-corrected visual acuity (BCVA) and complications were evaluated. A total of 100 eyes from 100 patients were included and were randomly assigned to five different groups, each one featuring a different suturing technique: interrupted (INT), single running (SRS), double running with two 10– 0 sutures (DRS), double running antitorque with two 10– 0 sutures (DRSa), double running with both 10– 0 and 11– 0 sutures (DRS with 11– 0).Results: There is a statistically significant difference in astigmatism after surgery between the double running sutures groups and the others with different techniques. However, there is no statistically significant difference between the INT and the SRS group; moreover, there is no statistically significant difference between the different groups with double running sutures (DRS, DRSa, DRS with 11– 0). There is no statistically significant difference in BCVA values among the five groups. The wound leak rate was 10% in the INT group, 5.3% in the SRS group and 0% in all groups with double running sutures.Conclusion: In penetrating keratoplasty surgery, the double running suture technique reduces postoperative astigmatism, provides faster visual rehabilitation and features lower complication rates when compared to techniques featuring single running and interrupted sutures. No significant difference in terms of postoperative astigmatism or complication rates was observed among patients receiving double running suture techniques.Keywords: astigmatism, penetrating keratoplasty, corneal suture technique, running suture, interrupted suture

The focus of this work is on the relationship between the quantitative structural characterization of bimetallic Au-Pd nanoparticles dispersed in an amorphous polymer matrix and their catalytic activity in the direct synthesis of hydrogen peroxide (DS reaction). Resonant X-ray powder diffraction with synchrotron radiation was employed to probe selectively and to reveal fine details of the structure of bimetallic nanoparticles embedded in the support. The semi-quantitative analysis of the resonant X-ray powdered diffraction data, made on a large number of metal nanoparticles, shows that in one of the polymer-supported Au-Pd catalyst for the DS reaction (P75) featured by an overall molar Pd/Au of about 5.54, the smallest metal nanoparticles (MNPs), which account for more than 99.9% of the total MNPs number and for more than 95% of the metal surface, are formed by practically pure palladium. The relative number of bimetallic alloyed nanoparticles is very small (less than 4 &times, 102 ppm) and they contribute to only about 2% of the total metal surface. In a second gold-enriched catalyst (P50) with an overall molar Pd/Au of 1.84, the proportion of the bimetallic alloyed nanoparticles increased to about 97% and they account for about 99% of the metal surface. As a result of the metal intermixing, the catalytic productivity for the DS reaction increased from 97 to 109 mmolH2O2/molH2, owing to the gold-promotion of palladium.

Catalyst Pd/K2621 (K2621 = strongly acidic macroreticular resin from Bayer) is an effective catalyst for the direct synthesis of hydrogen peroxide in methanol at temperatures near 0 °C, under batch reactor conditions. Reaction conditions are non-explosive in character and no addition of selectivity enhancers is required. Selectivity up to 70% at 50% conversion is achieved.

Moderately cross-linked co-polymers of N , N -dimethylacrylamide (DMAA), 2-(methylthio)ethyl methacrylate (MTEMA)and N , N ′-methylenebisacrylamide proves to be effective macromolecular ligands able to extract, Pd II and Au III from water solutions and to thoroughly disperse them inside the relevant polymer frameworks. Chemical reduction with NaBH 4 in water leads to M 0 /resin composites, in which size-control of the generated metal nanoclusters is achieved. Catalysts Au 0 /MTEMA-DMAA are active in the rapid oxidation of n -butanal to n -butanoic acid by dioxygen under mild conditions in water. Catalysts M 0 /MTEMA-DMAA and M 0 /C (M = Au, Pd) are active and moderalely chemoselective in the oxidation of n -butanol to n -butanal under the same conditions. Activity and chemoselectivity are positively affected by the co-presence of the two metal centres and for M 0 = Au and reach the best level when the very hydrophilic resin poly-(4-vinylpyridine-acrylic acid- N , N ′-methylenebisacrylamide) (VAM) is employed.

The functional resin poly-MTEMA–DMAA–MBA (MTEMA, 2-(methylthio)ethylmethacrylate; 4 mol%, DMAA, N,N-dimethylacrylamide, 88 mol%; MBA, N,N’-methylenebisacrylamide, 8 mol%) referred to as MTEMA–DMAA-4–8, behaves as a macromolecular ligand towards PdII and AuIII in water (Pd) and acetonitrile (Au). Mn/resin complexes are easily reduced with NaBH4 in water to M0/resin composites. The swollen polymer framework of MTEMA–DMAA-4–8 is seen to act as a “mold” leading to the production of ca. 2.5 nm nanoclusters for both elements. M0/MTEMA–DMAA-4–8 composites exhibit useful catalytic properties in various chemical transformations, under mild conditions in water.

The commercial macroreticular cation exchanger resin Lewatit K2621/H + and two gel-type resins bearing -SO 3 H and -SMe functionalities are used to produce two acidic Pd(0)/resin(H + ) and one non-acidic Pd(0)-Au(0)/resin catalysts that are tested in the direct synthesis of H 2 O 2 in methanol/ water (2.5:1) at -10°C and moderate H 2 and O 2 pressures. Molar yields in H 2 O 2 after 1.5 hours, range from 12.9% [Pd(0)-Au(0)/resin] to 46% [Pd(0)/ K2621/H + ].