Sodium Periodate Solution Research Articles

Mucoadhesive pickering nanoemulsions via dynamic covalent chemistry

Hypothesis. Submicron oil droplets stabilized using aldehyde-functionalized nanoparticles should adhere to the primary amine groups present at the surface of sheep nasal mucosal tissue via Schiff base chemistry. Experiments. Well-defined sterically-stabilized diblock copolymer nanoparticles of 20 nm diameter were prepared in the form of concentrated aqueous dispersions via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) using a water-soluble methacrylic precursor bearing cis-diol groups. Some of these hydroxyl-functional nanoparticles were then selectively oxidized using an aqueous solution of sodium periodate to form a second batch of nanoparticles bearing pendent aldehyde groups within the steric stabilizer chains. Subjecting either hydroxyl- or aldehyde-functional nanoparticles to high-shear homogenization with a model oil (squalane) produced oil-in-water Pickering macroemulsions of 20–30 µm diameter. High-pressure microfluidization of such macroemulsions led to formation of the corresponding Pickering nanoemulsions with a mean droplet diameter of around 200 nm. Quartz crystal microbalance (QCM) experiments were used to examine adsorption of both nanoparticles and oil droplets onto a model planar substrate bearing primary amine groups, while a fluorescence microscopy-based mucoadhesion assay was developed to assess adsorption of the oil droplets onto sheep nasal mucosal tissue. Findings. Squalane droplets coated with aldehyde-functional nanoparticles adhered significantly more strongly to sheep nasal mucosal tissue than those coated with the corresponding hydroxyl-functional nanoparticles. This difference was attributed to the formation of surface imine bonds via Schiff base chemistry and was also observed for the two types of nanoparticles alone in QCM studies. Preliminary biocompatibility studies using planaria indicated only mild toxicity for these new mucoadhesive Pickering nanoemulsions, suggesting potential applications for the localized delivery of hydrophobic drugs.

Hydrophilic Aldehyde-Functional Polymer Brushes: Synthesis, Characterization, and Potential Bioapplications.

Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) is used to polymerize a cis-diol-functional methacrylic monomer (herein denoted GEO5MA) from planar silicon wafers. Ellipsometry studies indicated dry brush thicknesses ranging from 40 to 120 nm. The hydrophilic PGEO5MA brush is then selectively oxidized using sodium periodate to produce an aldehyde-functional hydrophilic PAGEO5MA brush. This post-polymerization modification strategy provides access to significantly thicker brushes compared to those obtained by surface-initiated ARGET ATRP of the corresponding aldehyde-functional methacrylic monomer (AGEO5MA). The much slower brush growth achieved in the latter case is attributed to the relatively low aqueous solubility of the AGEO5MA monomer. X-ray photoelectron spectroscopy (XPS) analysis confirmed that precursor PGEO5MA brushes were essentially fully oxidized to the corresponding PAGEO5MA brushes within 30 min of exposure to a dilute aqueous solution of sodium periodate at 22 °C. PAGEO5MA brushes were then functionalized via Schiff base chemistry using an amino acid (histidine), followed by reductive amination with sodium cyanoborohydride. Subsequent XPS analysis indicated that the mean degree of histidine functionalization achieved under optimized conditions was approximately 81%. Moreover, an XPS depth profiling experiment confirmed that the histidine groups were uniformly distributed throughout the brush layer. Surface ζ potential measurements indicated a significant change in the electrophoretic behavior of the zwitterionic histidine-functionalized brush relative to that of the non-ionic PGEO5MA precursor brush. The former brush exhibited cationic character at low pH and anionic character at high pH, with an isoelectric point being observed at around pH 7. Finally, quartz crystal microbalance studies indicated minimal adsorption of a model globular protein (BSA) on a PGEO5MA brush-coated substrate, whereas strong protein adsorption via Schiff base chemistry occurred on a PAGEO5MA brush-coated substrate.

Preparation and evaluation of antibacterial wound dressing based on vancomycin-loaded silk/dialdehyde starch nanoparticles.

One of the main reasons infected wounds go untreated is that antibiotic-resistant bacteria mainly cause infection. Vancomycin is an antibiotic used against Gram-positive bacteria, such as MRSA, but it has limited intravenous use due to its toxicity. This study describes using a local drug delivery approach at the wound site. The aim is to prepare a silk dressing containing dialdehyde starch nanoparticles loaded with vancomycin that can cure infection through the controlled release of antibiotics. First, the starch was oxidized by sodium periodate solution and converted to dialdehyde starch. Dialdehyde starch was converted into nanoparticles by the microemulsion method. Simultaneously, with nanoparticle formation, the antibiotic vancomycin (VAN), added to the solution, was loaded into the dialdehyde starch nanoparticles (DASNP). The wound dressing (SF/DASNP/VAN) was prepared by adding nanoparticles containing antibiotics to the silk fibroin (SF) solution, and then, the solution containing the nanoparticles was freeze-dried, and the nanoparticles were placed inside the silk matrix. Drug release of dressings was performed by immersion in phosphate-buffered saline, and cytotoxicity by MTT assay and antibacterial properties of dressings were investigated by the inhibition zone method. The morphology of the SF/DASNP/VAN dressing, its biocompatibility, antibacterial efficiency, and antibiotic release kinetics were assessed. The synthesized dressing has the desired biocompatibility with 69% cell viability and shows antibacterial properties against MRSA with a growth inhibition zone diameter of 12mm. Also, VAN was successfully incorporated into the dressing, resulting in a 144-h continuous release profile. It may be concluded that the fabricated dressing based on silk and dialdehyde starch nanoparticles opens up a new option for topical administration of antibiotics. We believe its properties can be considered a new dressing for infectious wounds by reducing infection associated with controlled drug delivery.

Aldehyde-functional thermoresponsive diblock copolymer worm gels exhibit strong mucoadhesion.

A series of thermoresponsive diblock copolymer worm gels is prepared via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate using a water-soluble methacrylic precursor bearing pendent cis-diol groups. Selective oxidation using an aqueous solution of sodium periodate affords the corresponding aldehyde-functional worm gels. The aldehyde groups are located within the steric stabilizer chains and the aldehyde content can be adjusted by varying the periodate/cis-diol molar ratio. These aldehyde-functional worm gels are evaluated in terms of their mucoadhesion performance with the aid of a fluorescence microscopy-based assay. Using porcine urinary bladder mucosa as a model substrate, we demonstrate that these worm gels offer a comparable degree of mucoadhesion to that afforded by chitosan, which is widely regarded to be a ‘gold standard’ positive control in this context. The optimum degree of aldehyde functionality is approximately 30%: lower degrees of functionalization lead to weaker mucoadhesion, whereas higher values compromise the desirable thermoresponsive behavior of these worm gels.

Production and characterization of dialdehyde cellulose through green and sustainable approach

The objective of this study was to develop the efficient methods for dialdehyde cellulose (DAC) production, in which periodate solution was used as oxidant, and an electrochemically assisted system was applied to achieve green, efficient, low-cost and sustainable oxidization of cellulose. The microcrystalline cellulose (MCC) was pre-treated by alkali or ultrasound, and then oxidized to prepare DAC in the electrolyzer with aqueous solution of sodium periodate. Finally, the DAC was obtained by centrifugation and lyophilization. The prepared DAC materials were characterized by FTIR, XRD and SEM, and analyzed via aldehyde group contents, crystallinity index, water solubility index and water retention value. The introduction of active functional groups promoted cellulose hydration and swelling. Compared to the ultrasound pretreatment, the alkaline pretreatment had a great influence on the water solubility index and water retention value of cellulose. The aldehyde group contents of DAC increased after the MCC was oxidized by sodium periodate in the electrolyzer. Electrochemically assisted oxidation significantly decreased the crystallinity of the DAC, and the surface structure was smooth and soft, which can be attributed to the electrochemically assisted reaction that could regenerate the spent periodate in anode electrolytic chamber. When DAC was prepared under optimal conditions (current density: 0.075 A/cm2, periodate concentration: 0.6 mol/L, reaction time: 30 min), the regeneration efficiency of spent periodate reached about 93.4%.

A reversed-phase air-assisted dispersive liquid-liquid microextraction coupled with colorimetric paper-based analytical device for the determination of glycerol, calcium and magnesium in biodiesel samples

A cheap and simple procedure for the simultaneous colorimetric determination of glycerol, magnesium and calcium in biodiesel samples using a paper-based analytical device (PAD) was developed. A reversed-phase air-assisted dispersive liquid-liquid microextraction (RP-AA-DLLME) approach was proposed and used for glycerol, magnesium and calcium separation from biodiesel samples into aqueous phase (sodium periodate solution). After RP-AA-DLLME the obtained hydrophilic emulsion (biodiesel fuel in water) containing target analytes was introduced to a sample zone of the PAD, and as the emulsion penetrated through hydrophilic cellulose fibers to detection zones its destruction was observed. Colorimetric detection of calcium and magnesium with Eriochrome Black T and derivative of glycerol (formaldehyde) with acetylacetone on the detection zones of the PAD was implemented using conventional scanner and Corel® PHOTO-PAINT™ X7 software. Under optimal conditions, the calibration curves were linear in the ranges 100–300 μg g−1 for glycerol and 1–15 μg g−1 for calcium and magnesium. The limits of detection, calculated from a blank test based on 3σ, were 30 μg g−1 for glycerol and 0.3 μg g−1 for calcium and magnesium. The PAD was successfully applied for biodiesel samples analysis. Novelty statementA first paper-based analytical device for the simultaneous colorimetric determination of glycerol, calcium and magnesium in biodiesel samples was successfully developed. A novel approach for biodiesel samples pretreatment based on a reversed-phase air-assisted dispersive liquid-liquid microextraction was also proposed for the first time. The reversed-phase air-assisted dispersive liquid-liquid microextraction was coupled with paper-based analytical device and applied for the simultaneous colorimetric determination of glycerol, calcium and magnesium in biodiesel samples. In this study, it was found, that glycerol extraction kinetics from biodiesel samples to aqueous phase can be accelerated in the presence of periodate-ions due to analyte oxidation to water-soluble formaldehyde. This feature allowed improving glycerol extraction efficiency. The proposed procedure has several advantages including miniaturization, cost effectiveness and simplicity.

How To Shrink Paper Money: A Macroscopic Demonstration of the Malaprade Reaction

Shrinking paper money is a captivating and memorable demonstration of chemistry in action that can be carried out using minimal equipment and reagents. Paper bills can be shrunk down to ∼25% of their initial surface area by treating them with an aqueous solution of sodium periodate. The cellulose in the paper bill is oxidized to dialdehyde cellulose via the Malaprade reaction, and the resulting change in size of the paper money provides macroscopic evidence of the reaction. The chemical change that occurs in the cellulose can be confirmed by a Tollen’s test.

Efficient, Self-Terminating Isolation of Cellulose Nanocrystals through Periodate Oxidation in Pickering Emulsions.

Many efforts have been made to isolate native nanocrystals from raw materials in the last two decades, such as cellulose nanocrystals (CNCs), but existing methods still suffer from low yields, complicated synthesis processes, and nonuniform sizes of obtained CNCs. This study concerns a facile, self-terminating, and efficient method for the formation of uniform CNCs in high yields during the periodate oxidation process within Pickering emulsions. A biphasic system containing hexane with dissolved hexylamine and an aqueous solution of sodium periodate (NaIO4 ) was used as the reaction medium. Regulated by hexylamine, owing to its limited solubility in water, the pH value of the aqueous phase was enhanced to around 9.8, leading to the precipitation of sodium orthoperiodate (Na2 H3 IO6 ) nanoplates and thus the formation of the initial Pickering emulsions. During the gradual formation of cellulose nanofibers and then CNCs, CNCs were attracted to stabilize the interface of the Pickering emulsions, which prevented further decomposition of CNCs by the oxidizing agent in aqueous suspensions. Thus, this isolation strategy secured the efficient separation of CNCs based on their own particular amphiphilic properties and achieved a high yield of up to 56 wt %.

Fast assemble of polyphenol derived coatings on polypropylene separator for high performance lithium-ion batteries

Improving the wettability of liquid electrolyte to polyolefin separators plays a significant role in the fabrication of high performance lithium-ion batteries. Herein, we report a facile surface coating method to enhance the wetting capacity of commercially available polypropylene (PP) separator. Natural polyphenol tannic acid (TA) and sodium periodate are selected as the coating precursor and inorganic trigger, respectively. Coating formation is initiated by the absorption of tannin molecules on the separator surface and then triggered by a single contact (5min) with sodium periodate solution. After being modified, wettability of the separator can be significantly enhanced without damaging its original advantage properties, which accordingly resulted in higher electrolyte uptake and better interfacial compatibility. Furthermore, the LiCoO2/graphite full cells assembled with the modified separator displays an excellent cycle stability with coulombic efficiency exceeding 99.9% and superior rate performance. The ease, low cost and scalability of this coating process, combine with the general surface binding affinity of polyphenol, making this surface modification technique suitable to upgrade other inert substrates for various applications.

Organometallic Iridium Complex Containing a Dianionic, Tridentate, Mixed Organic-Inorganic Ligand.

A pentamethylcyclopentadienyl-iridium complex containing a tricyclic, dianionic, tridentate, scorpionate (facial binding), mixed organic-inorganic ligand was synthesized and characterized by single-crystal X-ray crystallography, as well as polynuclear NMR, UV-vis, and IR spectroscopies. The central cycle of the tridentate ligand consists of a modified boroxine in which two of the boron centers are tetrahedral, anionic borates. The complex is stable to hydrolysis in aqueous solution for >9 weeks at 25 °C but reacts with a 50 mM solution of sodium periodate within 12 s to form a periodate-driven oxygen evolution catalyst that has a turnover frquency of >15 s(-1). However, the catalyst is almost completely deactivated within 5 min, achieving an average turnover number of ca. 2500 molecules of oxygen per atom of iridium. Nanoparticles were not observed on this time scale but did form within 4 h of catalyst activation under these experimental conditions. The parent complex was modeled using density functional theory, which accurately reflected the geometry of the complex and indicated significant interaction of iridium- and boracycle-centered orbitals.

Paper-based enzymatic reactors for batch injection analysis of glucose on 3D printed cell coupled with amperometric detection

This report describes for the first time the development of paper-based enzymatic reactors (PERs) for the detection of glucose (Glu) in artificial serum sample using a 3D printed batch injection analysis (BIA) cell coupled with electrochemical detection. The fabrication of the PERs involved firstly the oxidation of the paper surface with a sodium periodate solution. The oxidized paper was then perforated with a paper punch to create microdisks and activated with a solution containing N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC). Glucose oxidase (GOx) enzyme was then covalently immobilized on paper surface to promote the enzymatic assay for the detection of Glu in serum sample. After the addition of Glu on the PER surface placed inside a plastic syringe, the analyte penetrated through the paper surface under vertical flow promoting the enzymatic assay. The reaction product (H2O2) was collected with an electronic micropipette in a microtube and analyzed in the 3D BIA cell coupled with screen-printed electrodes (SPEs). The overall preparation time and the cost estimated per PER were 2.5h and $0.02, respectively. Likewise the PERs, the use of a 3D printer allowed the fabrication of a BIA cell within 4h at cost of $5. The coupling of SPE with the 3D printed cell exhibited great analytical performance including repeatability and reproducibility lower than 2% as well as high sampling rate (30injectionsh−1) under low injection volume (10μL). The limit of detection (LD) and linear range achieved with the proposed approach was 0.11mmolL−1 and 1–10mmolL−1, respectively. Lastly, the glucose concentration level was successfully determined using the proposed method and the values found were not statistically different from the data achieved by a reference method at confidence level of 95%.

Kraft lignin/silica–AgNPs as a functional material with antibacterial activity

Advanced functional silica/lignin hybrid materials, modified with nanosilver, were obtained. The commercial silica Syloid 244 was used, modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane to increase its chemical affinity to lignin. Similarly, kraft lignin was oxidized using a solution of sodium periodate to activate appropriate functional groups on its surface. Silver nanoparticles were grafted onto the resulting silica/lignin hybrids. The systems obtained were comprehensively tested using available techniques and methods, including transmission electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, elemental analysis and atomic absorption spectroscopy. An evaluation was also made of the electrokinetic stability of the systems with and without silver nanoparticles. Conclusions were drawn concerning the chemical nature of the bonds between the precursors and the effectiveness of the method of binding nanosilver to the hybrid materials. The antimicrobial activity of the studied materials was tested against five species of Gram-positive and Gram-negative bacteria. The addition of silver nanoparticles to the silica/lignin hybrids led to inhibition of the growth of the analyzed bacteria. The best results were obtained against Pseudomonas aeruginosa, a dangerous human pathogen.

Synthesis and identification of rutin complete antigen and analysis its immunogenicity

Synthesis and identification of complete antigen of rutin, the traditional Chinese medicine active ingredient, and develop rapid detection of rutin using enzyme-linked immunoassay method (ELISA). Immunogenicity of the complete antigen was also studied. Prepare the complete antigen by sodium periodate solution and identified by UV scanning and SDS-PAGE test. Male New Zealand white rabbits were immunized by the antigen to obtain the antiserum. The results of UV analysis showed that the coupling ratio of complete antigen is 13: 1. SDS-PAGE display of the artificial antigen was delayed compared with bovine serum protein. The titer of rutin antibody is 1:4 000. The sensitivity of IC50 was 5.37 mg x L(-1), the lowest detection limit was 1 mg x L(-1), the average recovery was 102%, the intra and interspecific RSD were less than 10%, cross-reactivity rate of antibodies and other analogs were less than 1%. Rutin complete antigen was synthesized successfully, and the rapid detection of rutin by ELISA method was successfully established.

Electrospun catechol-modified poly(ethyleneglycol) nanofibrous mesh for anti-fouling properties.

Electrospun nanofibrous mesh composed of catechol-conjugated 8-arm PEG (8cPEGa) and thiolated PLGA (PLGA-SH) was prepared with various blending ratios of PLGA-SH and 8cPEGa. Cross-linking between the two polymers via catechol-thiol reactions and catechol-catechol conjugation was performed by brief soaking with sodium periodate solution. The chemical conjugation of PLGA-SH and 8cPEGa in the nanofibrous mesh was confirmed by the spectral differences of the Raman spectra and changes in the thermal properties. The crosslinked meshes showed lower degradation rates and their fibrous morphologies remained intact even after 15 days. When the blend ratio of 8cPEGa was increased from 0 to 50%, the crosslinked meshes showed a dramatic decrease in the water-contact angles due to the surface-exposed PEG chains tethered on the mesh. The crosslinked meshes had superior anti-fouling effect on protein and mammalian cell binding in proportion to the amount of 8cPEGa in the mesh compared to non-crosslinked meshes.

Characterization and controlled release aloe extract of collagen protein modified cotton fiber

For exploiting the novel multifunctional cotton fibers, a collagen protein modified cotton fiber (CPMCF) was prepared by the oxidation of cotton fiber with sodium periodate solution and subsequent crosslinking reaction with an aqueous solution of collagen protein in acetic acid. Infrared spectra and X-ray photoelectron spectrometry (XPS) analysis of the CPMCF illuminated that the CN double bond was formed through the imine reaction of the aldehyde group on oxidized cotton fiber with the amino group of collagen protein. X-ray diffractograms indicated that the crystallinity of the oxidized cotton fiber increased from 65.6 to 69.3% after collagen protein treatment. Scanning electron microscopy photographs displayed that the collagen protein combined on the surface of oxidized cotton fiber. The resulting optimum conditions to prepare the CPMCF achieved the sufficient aldehyde groups in oxidized cotton fiber and the collagen protein content on CPMCF, whereas the mechanical strength of the oxidized cotton fiber had no significant change. Meanwhile, a model experiment for the controlled release of aloe anthraquinone extract on CPMCF showed a satisfactory result compared with those release of the original cotton fiber, demonstrated potential application of the synthetic collagen protein–cotton fiber as a carrier for the sustained release of drugs.

Flow injection analysis of ketoprofen based on the order transform second chemiluminescence reaction

This paper explores an order-transform-second-chemiluminescence (OTSCL) method combining the flow injection technique for the determination of ketoprofen. When ketoprofen solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate solution was injected into the reaction mixture of ketoprofen and alkaline luminol, a new chemiluminescence (CL) reaction was initiated and strong CL signal was detected. A mechanism for the OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristic, UV–visible absorption and chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of ketoprofen over the range of 2.0 × 10 −7 to 1.0 × 10 −5 mol/L with a correlation coefficient of 0.9950 and a detection limit of 8.0 × 10 −9 mol/L (3 σ). The relative standard deviation for 11 repetitive determinations of 1.0 × 10 −6 mol/L ketoprofen is 2.9%. The utility of this method was demonstrated by determining ketoprofen in pharmaceutical formulations without interference from its potential impurities.

Plasmin Is Essential in Preventing Periodontitis in Mice

Periodontitis involves bacterial infection, inflammation of the periodontium, degradation of gum tissue, and alveolar bone resorption, which eventually leads to loss of teeth. To study the role of the broad-spectrum protease plasmin in periodontitis, we examined the oral health of plasminogen (Plg)-deficient mice. In wild-type mice, the periodontium was unaffected at all time points studied; in Plg-deficient mice, periodontitis progressed rapidly, within 20 weeks. Morphological study results of Plg-deficient mice revealed detachment of gingival tissue, resorption of the cementum layer, formation of necrotic tissue, and severe alveolar bone degradation. IHC staining showed massive infiltration of neutrophils in the periodontal tissues. Interestingly, doubly deficient mice, lacking both tissue- and urokinase-type plasminogen activators, developed periodontal disease similar to that in Plg-deficient mice; however, mice lacking only tissue- or urokinase-type plasminogen activator remained healthy. Supplementation by injection of Plg-deficient mice with human plasminogen for 10 days led to necrotic tissue absorption, inflammation subsidence, and full regeneration of gum tissues. Notably, there was also partial regrowth of degraded alveolar bone. Taken together, our results show that plasminogen is essential for the maintenance of a healthy periodontium and plays an important role in combating the spontaneous development of chronic periodontitis. Moreover, reversal to healthy status after supplementation of Plg-deficient mice with plasminogen suggests the possibility of using plasminogen for therapy of periodontal diseases.

Imine Bond Characterization and Properties for Controlled Release Drugs of Collagen Protein Cross-Linked Cotton Fiber

For exploiting the novel multifunctional ecological cotton fibers, a new cotton fiber with the collagen protein cross-linking (CPCCF) was prepared by the limited selective oxidation of a cotton thread with sodium periodate solution and subsequent treatment with a solution of collagen protein at 40°C in aqueous acetic acid. FT-IR spectra of the CPCCF suggested that the imine covalent bond between the collagen protein and the oxidized cotton fiber was formed through a series of reaction. X-ray diffractograms analysis showed that the crystallinity of oxidized cotton fiber after collagen protein treatment increased slightly. Meanwhile, Scanning electron microscopy photographs illuminated that the modification with collagen protein occurred on the surface of cotton fiber. Kjeldahl nitrogen analysis of the CPCCF showed that the maximum percentage of collagen protein introduced into cotton fiber was 1.68% (w/w). However, the breaking strength of the cotton thread oxidized partially by sodium periodate at the concentration of less than 2.0 mg ml-1 did not decrease much. Furthermore, a model experiment for the controlled release drugs was performed using aloe anthraquinone, components of a Chinese medicine, suggested potential usefulness of the CPCCF as a carrier for the controlled release drugs.

Oxidation of Flax Fiber with Sodium Periodate Solution

Oxidation of Flax Fiber with Sodium Periodate Solution

Rhodium(III) catalyzed oxidation of dextrose and maltose by acidic solution of sodium periodate : A kinetic study

The kinetics of rhodium(ΙΙΙ) catalyzed oxidation of dextrose and maltose by sodium periodate in acidic medium has been studied in the temperature range 30-45 °C. The reaction is carried out in the presence of mercuric acetate as a scavenger for iodide ion. The rate shows first order kinetics with respect to the oxidant, sodium periodate and Rh ΙΙΙ for both dextrose and maltose. A suitable mechanism in conformity with the kinetic observations has been proposed and the thermodynamic parameters computed.