Whole genome integrity and enhanced developmental potential in ram freeze-dried spermatozoa at mild sub-zero temperature

Freeze-dried spermatozoa typically shows a reduction in fertility primarily due to the DNA damage resulting from the sublimation process. In order to minimize the physical/mechanical damage resulting from lyophilization, here we focused on the freezing phase, comparing two cooling protocols: (i) rapid-freezing, where ram sperm sample is directly plunged into liquid nitrogen (LN-group), as currently done; (ii) slow-freezing, where the sample is progressively cooled to − 50 °C (SF-group). The spermatozoa dried in both conditions were analysed to assess residual water content by Thermal Gravimetric Analysis (TGA) and DNA integrity using Sperm Chromatin Structure Assay (SCSA). TGA revealed more than 90% of water subtraction in both groups. A minor DNA damage, Double-Strand Break (DSB) in particular, characterized by a lower degree of abnormal chromatin structure (Alpha-T), was detected in the SF-group, comparing to the LN-one. In accordance with the structural and DNA integrity data, spermatozoa from SF-group had the best embryonic development rates, comparing to LN-group: cleaved embryos [42/100 (42%) versus 19/75 (25.3%), P < 0.05, SL and LN respectively] and blastocyst formation [7/100 (7%) versus 2/75 (2.7%), P < 0.05, SF and LN respectively]. This data represents a significant technological advancement for the development of lyophilization as a valuable and cheaper alternative to deep-freezing in LN for ram semen

Design and synthesis of plasticizing fillers based on zirconium phosphonates for glycerol-free composite starch films

Novel starch-based composite films were prepared by solution casting from gelatinized starch, using a new class of layered zirconium hydroxyalkyl aminophosphonates, ZrF(O 3PCH 2) 2NH(CH 2) nOH (n = 3, 4, 5), as fillers/plasticizers. These compounds were specifically designed and synthesized for this application in order to support organic polar groups, able to interact with the polymer, on robust inorganic layers. Their structures were solved ab initio from powder X-ray diffraction data. The films, loaded with 2 wt% of fillers, were studied by means of various techniques such as X-ray diffraction, scanning and transmission electron microscopy, thermogravimetry, and stress-strain tests. The obtained results highlighted the double role played by the fillers as a reinforcement for the polymer matrix and as plasticizing agents: the composites showed improved thermal and mechanical properties, along with a significant reduction of volume swelling, if compared with the glycerol-plasticized films. © 2012 The Royal Society of Chemistry

Conductivity and hydration of sulfonated polyethersulfone in the range 70-120 degrees C: Effect of temperature and relative humidity cycling

Proton conductivity and hydration of sulfonated polyethersulfone (SPES) membranes, with ion exchange capacity of 1.31 meq g(-1), is determined under different conditions of temperature, in the range 70-120 degrees C, and relative humidity (RH) in the range 50-90%. Conductivity measurements are performed by the impedance technique, and the impedance data are analyzed on the basis of a simple equivalent circuit in order to compare the evolution of the membrane conductivity with that of the electrical capacitance of the electrode-electrolyte interface during heating and cooling runs. Temperature cycling at constant RH, as well as RH cycling at constant temperature,give rise to hydration hysteresis and to the concomitant conductivity hysteresis. The highest conductivity (4.5.10(-2) S cm(-1)) is measured at 100 degrees C-90% RH with 8.4 water molecules per sulfonic group. The hysteresis associated with temperature cycling is avoided by filling SPES with zirconium phosphate which makes hydration easier at low temperatur

Crosslinked SPES-SPPSU membranes for high temperature PEMFCs

Highly sulfonated polyethersulfone (SPES; lone exchange capacity = 3.2 meq/g) and polyphenylsulfone (SPPSU; ion exchange capacity = 3.2 meq/g) were synthesized. To get high thermal and chemical stability, a blend membrane was prepared by the composite of SPES and SPPSU. The SPES-SPPSU blend membrane after the annealing treatment at 180 degrees C was stable in water and other organic solvents, and the thermal stability was also more increased than that of pristine SPES and SPPSU polymers due to the crosslinking formation among SPES and SPPSU. The maximum conductivity of 0.12 S/cm was obtained at the temperature of 140 degrees C and RH 90%. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Synthesis, crystal structure, and proton conductivity of one-dimensional, two-dimensional, and three-dimensional zirconium phosphonates based on glyphosate and glyphosine

The reaction of two small phosphono-amino acids based on glycine (glyphosine and glyphosate) with zirconium under mild conditions led to the attainment of three related zirconium derivatives with 1D, 2D, and 3D structures of formulas ZrF[H3(O3PCH2NHCH 2COO)2] (1), Zr3H8[(O 3PCH2)2NCH2COO]4· 2H2O (2), and Zr[(O3PCH2)(HO 3PCH2)NHCH2COOH]2·2H 2O (3), respectively, whose structures were solved by X-ray powder and single-crystal diffraction data. The glyphosate derivative has 1D ribbon-type structure whereas the dimensionality of the glyphosine-derived materials (2D and 3D) can be tuned by changing the synthesis conditions. The low-dimensional compounds (1 and 2) can be directly produced in the form of nanoparticles with different size and morphology whereas the 3D compound (3) has a higher crystallinity and can be obtained as single crystals with a prismatic shape. The different structural dimensionality reflects the shape and size of the crystals and also differently affects the proton conductivity properties, measured over a wide range of temperature at 95% relative humidity. Their high thermal and chemical stability together with the small size may promote their use as fillers for polymeric electrolyte membranes for fuel cells applications. © 2013 American Chemical Society

Evaluation of Membranes Transport Properties for PEMFC: A New Approach

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Layered metal(IV) phosphonates with rigid pendant groups: New synthetic approaches to nanosized zirconium phosphate phenylphosphonates

Single phase mixed zirconium phosphate phenylphosphonates, ZrP(PP) x, were prepared by two different synthetic approaches: reaction of gels of nanosized α-zirconium phosphate in propanol with solutions of phenylphosphonic acid (H2PP), leading to the topotactic exchange of monohydrogen phosphate groups with phenylphosphonate groups, and precipitation from propanol solutions of H2PP, phosphoric acid, and zirconyl propionate. In both cases, propanol intercalated compounds were obtained. The x values of the ZrP(PP)x materials prepared by topotactic anion exchange ranged from 0.37 to 0.56 for (H2PP/Zr) molar ratios in the range 0.52-4.16 and [H2PP] = 0.1 M, while a maximum x value of 0.73 was only reached at 60 C, with (H2PP/Zr) = 4.16 and [H2PP] = 0.31 M. Direct precipitation of ZrP(PP)x provided samples with 0.13 ≤ x ≤ 1.54, for H2PP molar fractions in the range 0.05-0.5 and (P/Zr) molar ratio = 6. At 90% relative humidity, the (H2O/Zr) molar ratio for the precipitated ZrP(PP)x powder samples increased in the range 1.3-3.0 with increasing x and resulted in being higher than that of nanosized ZrP (0.8). The analysis of the X-ray diffraction patterns of the gel and powder samples, together with the hydration data of the powder samples, suggested a structural model in which the random distribution of the phosphate and phenylphosphonate groups creates cavities which can accommodate propanol molecules in the gel samples and water molecules in the hydrated powder samples. © 2014 American Chemical Society