The Experts below are selected from a list of 33075 Experts worldwide ranked by ideXlab platform
Bjørn E. Christensen - One of the best experts on this subject based on the ideXlab platform.
-
Periodate oxidation of polysaccharides for modification of chemical and physical properties
Carbohydrate Research, 2010Co-Authors: Kare Andre Kristiansen, Antje Potthast, Bjørn E. ChristensenAbstract:A limited degree (typically 1–20%) of Periodate oxidation of polysaccharides may give rise to derivatives with entirely altered chemical and physical properties. Notably, the ring opening caused by Periodate leads to the formation of highly flexible ‘hinges’ in otherwise rather semiflexible or rigid structures. This review highlights selected examples with the main focus on Periodate oxidation of alginates, chitosans, hyaluronan, scleroglucan/schizophyllan, and cellulose.
-
Periodate oxidation of chitosans with different chemical compositions
Carbohydrate research, 2005Co-Authors: Inger M. N Vold, Bjørn E. ChristensenAbstract:Abstract Periodate oxidation of chitosans with different chemical compositions were investigated by determining the consumption of Periodate consumed, and the amount of ammonia and formaldehyde liberated during the reaction. Oxidised chitosans were further characterised by size-exclusion chromatography with online multi-angle light scattering (SEC-MALLS) to obtain the molecular weight distributions, and by elemental analysis to obtain the N/C ratio. Chitosans became only partially oxidised by Periodate, reaching degrees of oxidation around 0.5, when oxidising with excess Periodate. Overconsumption of Periodate is attributed to the extensive depolymerisation, which occurs concomitantly with the oxidation, thereby exposing novel reducing and non-reducing ends which consume additional Periodate. Both the rate and extent of overoxidation, and the rate of depolymerisation decreased with increasing F A . A chitosan-specific degradation mechanism is probably involved in the depolymerisation in addition to the general free-radical-mediated degradation.
Juho Antti Sirviö - One of the best experts on this subject based on the ideXlab platform.
-
Review: Periodate oxidation of wood polysaccharides-Modulation of hierarchies.
Carbohydrate polymers, 2020Co-Authors: Tiina Nypelö, Barbara Berke, Stefan Spirk, Juho Antti SirviöAbstract:Abstract Periodate oxidation of polysaccharides has transitioned from structural analysis into a modification method for engineered materials. This review summarizes the research on this topic. Fibers, fibrils, crystals, and molecules originating from forests that have been subjected to Periodate oxidation can be crosslinked with other entities via the generated aldehyde functionality, that can also be oxidized or reduced to carboxyl or alcohol functionality or used as a starting point for further modification. Periodate-oxidized materials can be subjected to thermal transitions that differ from the native cellulose. Oxidation of polysaccharides originating from forests often features oxidation of structures rather than liberated molecules. This leads to changes in macro, micro, and supramolecular assemblies and consequently to alterations in physical properties. This review focuses on these aspects of the modulation of structural hierarchies due to Periodate oxidation.
-
regeneration and recycling of aqueous Periodate solution in dialdehyde cellulose production
Journal of Wood Chemistry and Technology, 2013Co-Authors: Henrikki Liimatainen, Juho Antti Sirviö, Heikki Pajari, Osmo E O Hormi, Jouko NiinimakiAbstract:Abstract The regeneration of aqueous iodate solution from the regioselective Periodate oxidation of softwood cellulose pulp to dialdehyde cellulose using hypochlorite as a secondary oxidant was studied. The influence of oxidation time on the pulp dissolution and regeneration efficacy was examined in particular. In addition, the recycling of regenerated Periodate solution back to oxidation was clarified. The solutions from the 10 and 15 min oxidations were regenerated with 100% conversion efficacy when 1.2–1.4 times the stoichiometric amounts of hypochlorite were used. However, the regeneration efficacy decreased when the reaction time in the oxidation increased to 30 min because the content of soluble impurities, which consumed the hypochlorite in the side-reactions, increased significantly as the oxidation reaction proceeded. The regenerated solutions possessed good oxidation performance, showing that Periodate was successfully regenerated using hypochlorite and supporting the assumption that Periodate c...
-
Periodate oxidation of cellulose at elevated temperatures using metal salts as cellulose activators
Carbohydrate Polymers, 2011Co-Authors: Juho Antti Sirviö, Henrikki Liimatainen, Jouko Niinimaki, Uula Hyvakko, Osmo E O HormiAbstract:The birch cellulose is effectively oxidized to the dialdehyde cellulose (DAC) at elevated temperatures by sodium Periodate. Even though Periodate decomposes at 55 °C and above with time, higher temperatures can be used if the oxidation time is sufficiently short and it has now been shown that temperatures up to 85 °C can be used during the oxidation. Lithium chloride can be used to further improve the oxidation efficiency. Other metal salts, such as calcium chloride can be used as well. These conditions provides possibility to use a lower amount of Periodate to obtain high aldehyde contents in DAC.
Kare Andre Kristiansen - One of the best experts on this subject based on the ideXlab platform.
-
Periodate oxidation of polysaccharides for modification of chemical and physical properties
Carbohydrate Research, 2010Co-Authors: Kare Andre Kristiansen, Antje Potthast, Bjørn E. ChristensenAbstract:A limited degree (typically 1–20%) of Periodate oxidation of polysaccharides may give rise to derivatives with entirely altered chemical and physical properties. Notably, the ring opening caused by Periodate leads to the formation of highly flexible ‘hinges’ in otherwise rather semiflexible or rigid structures. This review highlights selected examples with the main focus on Periodate oxidation of alginates, chitosans, hyaluronan, scleroglucan/schizophyllan, and cellulose.
William S. Eck - One of the best experts on this subject based on the ideXlab platform.
-
Acute and subacute oral toxicity of Periodate salts in rats.
Regulatory toxicology and pharmacology : RTP, 2016Co-Authors: Emily May Lent, Lee C. B. Crouse, William S. EckAbstract:Abstract Periodate salts are being developed as potential replacements for perchlorate due to potential health hazards associated with exposure to perchlorate. The aim of this study was to investigate acute and subacute effects of Periodate salts in rats. Acute oral toxicity of potassium and sodium Periodate was determined using the Sequential Stage-Wise Probit method. The LD 50 for potassium Periodate was 732 (95% CI = 539–838, slope = 13.4) and 685 mg/kg (95% CI = 580–809, slope = 10.6) for females and males, respectively. The LD 50 for sodium Periodate was 318 (95% CI = 292–347, slope = 24.3) and 741 mg/kg (95% CI = 704–779, slope = 31.2) for females and males, respectively. In the subacute study, rats were administered sodium Periodate at five doses (1/16 LD 50 up to LD 50 ) or distilled water for 14-days via oral gavage. Female rats in the 318 mg/kg-day group and male rats in the 185, 370, and 741 mg/kg-day groups exhibited moribundity, kidney toxicity, uremia, and a stress response. BMDL 10 s of 17.2 and 33.7 mg/kg-day were derived for females and males, respectively. Comparison with the NOAEL for perchlorate-induced thyroid toxicity in rats (0.009 mg/kg-day) suggests sodium Periodate is less toxic than perchlorate on a subacute basis.
-
Periodates as Potential Replacements for Perchlorates in Pyrotechnic Compositions
Propellants Explosives Pyrotechnics, 2016Co-Authors: Jason S. Brusnahan, Anthony P. Shaw, Jared D. Moretti, William S. EckAbstract:The Periodate salts NaIO4 and KIO4 are critically evaluated as potential replacements for KClO4 in pyrotechnic compositions. Key differences between the physical and chemical properties of the Periodate and perchlorate oxidizers are presented. The thermochemical characteristics of binary flash/incendiary compositions containing Al, MgAl, or Mg as the fuel and Periodate or perchlorate salts as oxidizers were studied using the FactSage 6.4 software package. The computational results are compared to existing experimental data. The tendency of NaIO4 to form gaseous Na, an emitter of yellow light, in such reactions promotes high luminous efficiencies. Due to a lack of literature addressing the stability and aging characteristics of Periodate-containing formulations, it is recommended that further research should be undertaken to evaluate potential chemical incompatibilities. Other concerns, including the availability and toxicological properties of the Periodates, are also discussed.
Jalal Basiri Parsa - One of the best experts on this subject based on the ideXlab platform.
-
high efficient photocatalytic fuel cell integrated with Periodate activation for electricity production by degradation of refractory organics
Journal of Power Sources, 2021Co-Authors: Tayebeh Parvizi, Jalal Basiri ParsaAbstract:Abstract In this work, a novel photocatalytic fuel cell integrated with a Periodate activation process was used for the degradation of pollutants and synchronous generation of electricity. This designed system is comprised of reduced graphene oxide/TiO2 nanotubes photoanode and polypyrrole/multi-walled carbon nanotube cathode. Herein, a synergistic procedure was presented by introducing Periodate in the photo fuel cell system. Compared to the Periodate activation process and single photo fuel cell, the combined system displayed better performance. The addition of Periodate to the photo fuel cell system extended the radical reactions from the surface of electrodes to the entire solution. Meanwhile, Periodate as an electron acceptor efficiently suppressed the recombination of electron/hole pairs. Hence, the photo fuel cell/Periodate system significantly increased the degradation efficiency by 54℅ and electricity generation by 87℅ relative to the single photo fuel cell. The highest degradation efficiency of 99℅ and maximum power density of 1500 μW cm−2 were obtained using citric acid as the organic compound. The practical factors, including initial pH, Periodate concentration, and organic compound concentration, were optimized. The radical quenching tests revealed that HO•, singlet oxygen, IO4•, IO3•, •O2−, and holes played important roles in the degradation process.
