Redfern Method Research Articles

Investigation of DNA binding and bioactivities of furan cored Schiff base Cu (II), Ni (II), and Co (III) complexes: Synthesis, characterization and spectroscopic properties

Novel binary metal complexes,1[Cu(FMIMBMOP)2],2[Ni(FMIMBMOP)2] and3[Co(FMIMBMOP)3], where FMIMBMOP (2‐((E)‐((furan‐2‐yl)methylimino)methyl)‐4‐bromo‐6‐methoxyphenol), were synthesized and characterized using different analytical techniques. Result of spectral studies reveals that square planar geometry is assigned for Cu (II) and Ni (II) complexes, whereas octahedral geometry is assigned for Co (III) complex. The thermodynamic and kinetic parameters for the degradation of the complexes were ascertained by Coats–Redfern method for thermogravimetric data attained from thermogravimetric analysis (TGA). The stability of the complexes has been calculated from quantum chemical parameters using highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. The DNA binding of complexes was studied by using ultraviolet–visible (UV–Vis) spectroscopic technique; screening their ability to bind to calf thymus DNA (CT‐DNA) showed that the complexes can interact with CT‐DNA through intercalation mood, where theKbvalues are 2.59 ± 0.01 × 104, 7.43 ± 0.03 × 103, and 6.73 ± 0.02 × 104 M−1for1,2, and3, respectively. Stern–Volmer quenching constant (Ksv) values ranged from 2.32 ± 0.03 × 103to 1.66 ± 0.02 × 104 M−1were calculated for complexes from fluorescence studies. The oxidative and photolytic cleavage of supercoiled pBR322 DNA was studied and found that the complexes have cleaved this DNA effectively. The novel metal complexes have shown significant antioxidant activity against DPPH radical. The antibacterial activity of Schiff base and its metal complexes screened againstBacillus thuringiensis,Streptococcus pneumoniae,Escherichia coli, andPseudomonas putidawas investigated, and the results indicated that the metal complexes have better results than Schiff base ligand. The catalytic ability of metal complexes1,2, and3was found to be3 > 1 > 2.

Combustion Characteristics and Kinetic Analysis of Biomass Pellet Fuel Using Thermogravimetric Analysis

Biomass pellet fuel is one of the development directions of renewable energy. The purpose of the article is to study the combustion characteristics of five kinds of biomass pellet fuel that can be used as biomass fuel and analyze their combustion kinetics. The thermogravimetric method (TG method) was used to analyze the combustion characteristics of five kinds of biomass pellet fuel and to calculate the index S of comprehensive combustion characteristic. The Arrhenius equation and the Coats–Redfern method were used to analyze the combustion kinetics of five kinds of biomass pellet fuel. The activation energy and pre-exponential factor were obtained according to different temperature ranges. Conclusions are as follows: The pyrolysis of five kinds of biomass pellet fuel mainly includes three stages: (1) water evaporation stage, (2) volatile component combustion stage, (3) fixed carbon oxidation stage. The TG curves of five kinds of biomass pellet fuel are roughly the same at the same heating rate. The peaks of thermal weight loss rate and maximum degradation rate are both in the high temperature range. The differential thermal gravity (DTG) curves of five kinds of biomass pellet fuel have an obvious peak. The peak temperature of the largest peak in the DTG curves is 280–310 °C. The first-order reaction equation is used to obtain the kinetic parameters in stages. The correlation coefficients are bigger than the value of 0.92. The fitting results are in good agreement with the experimental results. The activation energy of each sample is basically the same in each stage. The value in the volatile matter combustion stage is 56–542 kJ/mol, and the activation energy of the carbon layer slowly increases rapidly. The five kinds of biomass pellet fuels have good combustion characteristics and kinetic characteristics, and they can be promoted and applied as biomass pellet fuels in the future.

Evaluation of thermokinetics methodology, parameters, and coke characterization of co-pyrolysis of bituminous coal with herbaceous and agricultural biomass

In this paper, conventional thermogravimetric analysis and a new congruent–mass thermogravimetric analysis were used to study the reaction mechanism of the co-pyrolysis process of coal and biomass in the thermogravimetric analyzer, the effects of heating rate and carrier gas flow rate on co-pyrolysis were investigated, and kinetic analysis was conducted for the major pyrolysis stages to explore whether there was a synergistic effect in the co-pyrolysis process. The surface morphology of pyrolytic coke was evaluated by the fractal dimension method. The results show that congruent–mass thermogravimetric analysis can compare the interactions in the co-pyrolysis process more intuitively and reduce the influence of initial mass on the determination of interaction relationship. Synergistic effect appears in co-pyrolysis of coal and biomass. With the increase of heating rate, the thermogravimetric hysteresis appeared and the thermogravimetric curve gradually moved to the high temperature region. With the increase of carrier gas flow rate, the synergistic effect weakens. The kinetics of different reaction stages was analyzed by Coats–Redfern method; the results show that the activation energy required in the main co-pyrolysis stage of the mixture is lower than that in the pyrolysis stage alone. The micromorphology shows that biomass coke has a more developed pore structure than coal, and the box dimension indicates that co-pyrolysis increases the surface irregularity of coke. It is of great significance to judge the interaction mechanism of two or even multiple mixed samples in the process of co-pyrolysis.

Kinetics of pyrite multi-step thermal decomposition in refractory gold sulphide concentrates

The behaviour and kinetics of pyrite thermal decomposition were studied in a nitrogen atmosphere using thermogravimetric analysis. Pyrite decomposition was confirmed in two successive steps via SEM–EDS analysis as follows: pyrite → pyrrhotite → troilite. The overlapping peaks of pyrite were accurately separated via Asym2Sig deconvolution. The kinetic parameters were evaluated using the Kissinger–Akahira–Sunose, Kissinger, Flynn–Wall–Ozawa, Friedman, and Coats–Redfern methods. The kinetics mechanism was established via a data comparison of model-free and model-fitting methods and was further verified by comparing microstructural changes between pyrite roasting, which was proven to be appropriate by comparing the fitted reconstruction and experimental curves. The decomposition of pyrite was random and formed a porous structure. Pyrite has a better thermal stability than pyrrhotite. The kinetics of the two steps were consistent with the random nucleation and growth of the Avrami–Erofeev model. The relationship in terms of temperature for the thermodynamic activation parameters was established, and the parameters were calculated at characteristic temperatures.

Pyrolysis characteristics of oil shale semi-coke and its extracted bitumen

Fushun oil shale semi-coke and its extracted bitumen were prepared for analyzing their pyrolysis characteristics by TG–DTG, TG–FTIR, and Py–GC/MS. Semi-coke was the residue of oil shale pyrolyzed to 450 °C, and extracted bitumen was the organic matter extracted from semi-coke with [Bmim]Cl/NMP mixed solvents. Gaussian fitting method was used to analyze the proportions of bond cleavage reactions occured during the pyrolysis to 700 °C at a heating rate of 20 °C/min. Results showed that 3–4 kinds of bond cleavages were mainly involved. The outstanding pyrolysis behaviors were contributed by the cleavages of CalCal and weak bonds (including volatilization). The kinetic parameters based on Coats–Redfern method were calculated from the points for each pyrolysis stage and bond cleavage reaction. The evolution processes of typical gaseous products and distributions of flash pyrolysis products were displayed in detail, exhibiting the prominent roles of aliphatic compounds, CH4, and CO2. Moreover, the releases of the typical gaseous products for semi-coke tended to occur at higher temperatures.

Slow pyrolysis of an LDPE/PP mixture: Kinetics and process performance

High- and low-density polyethylene (HDPE and LDPE) and polypropylene (PP) are the most common polymers among plastic waste as they have multiple commercial applications. This study focused on thermal degradation characteristics and kinetic of a plastic mixture with a composition of 92.5 wt% LDPE and 7.5% PP. Thermal decomposition characteristics of the plastic mixture was analysed through thermo-gravimetric analysis (TGA). The overall kinetic of the process was studied using the modified Coats−Redfern method and the Ozawa-Flynn-Wall (OFW) method. The apparent activation energy (E) and pre-exponential factor (A) obtained were 316.0 kJ/mol; 8.09E+21 min−1 and 311.5 kJ/mol; 4.35E+21 min−1, respectively. Slow pyrolysis of the analysed mixture was carried out in a semi-batch reactor under atmospheric pressure and nitrogen atmosphere and three different pyrolysis temperatures were investigated: 420 °C, 450 °C and 500 °C. H2, CH4, C2H4, C2H6 and C3H8 were the main components of the gas phase. Liquid (oil/wax phase) yields increased with increasing operative temperature from 42% at 420 °C to 62% at 500 °C. On the other hand, solid phase showed a specular behaviour compared to the oil/wax phase, decreasing from 21% to 5% in the considered temperature range. On the contrary, gas phase did not change much with pyrolysis temperature, with a decrease from 37% at 420 °C to 34% at 500 °C. Products’ energy yields were also estimated at 420 °C. They ranged from 7.4% to 37.8% and 43.0% for solid, gas and oil fraction, respectively. Oil fraction collected from pyrolysis at 420 °C was also characterized.

Thermal decomposition behaviour and numerical fitting for the pyrolysis kinetics of 3D spongin-based scaffolds. The classic approach

The kinetic parameters of thermal degradation of 3D skeletal biopolymer spongin - isolated from the marine demosponge Hippospongia communis, using thermogravimetric analysis (TG) were evaluated. The kinetic parameters of the pyrolysis in a nitrogen atmosphere were calculated using standard methods, including a model-fitting approach (Coats–Redfern method) and the model-free iso-conversional Friedman, Kissinger–Akahira–Sunose (KAS) and Ozawa–Flynn–Wall (OFW) methods. Based on the kinetic parameters obtained from the respective equations, the changes of entropy (ΔS), enthalpy (ΔH), and free Gibbs energy (ΔG) were evaluated using the theory of the active complex of the reagent. It was found that the chemical reaction model best describes the experimental data. The activation energies calculated by the Coats–Redfern method were in the range 39.3–48.7 kJ/mol. The calculated values of kinetics parameters are slightly lower than for the commercial polyurethane foams. Nevertheless, this study provides a comprehensive insight into the pathway, mechanism, and outcomes of pyrolysis of spongin-based scaffolds with the relation to the physicochemical characteristics of finally obtained carbon materials. Moreover, a critical discussion of the obtained results is given, with regard to the physical meaning of the applied approximations.

A comprehensive study on the combustion kinetic modeling of typical electronic plastic waste—television set (TV) plastic shell

ABSTRACT Electronic waste is the fastest growing waste stream and one of the most significant constituents is electronic plastics. In this study, the combustion kinetic of typical electronic plastic waste—television set (TV) plastic shell—was investigated using two basic kinetic methods. The reaction mechanism and kinetic compensation effect were probed as well. The thermogravimetric analysis (TGA) revealed that its degradation process can be divided into four stages, namely, reaction initiation stage (20–300 °C), major reaction stage (300–450 °C), minor reaction stage (450–600 °C), and reaction cessation stage (600–1,000 °C). The activation energy (E) were calculated and indicated that, the kinetic parameters from six model-free methods gradually decreased with α increasing from 0.1 to 0.35, and then slightly increased. The Flynn--Wall--Ozawa (FWO) method was more reliable and E values decreased from 155.0 to 147.51 kJ/mol with α range of 0.1–0.35, then gradually increased to 165.21 kJ/mol. Within the Coats--Redfern method, the first-order (F1) model had higher coefficient of determination (R2) and comparable E values with that from FWO method. The result of kinetic compensation effect confirmed that the compensation effect existed between E and A during the plastic waste combustion. A linear relationship lnA = 0.183E-3.11 (R2 = 0.991) was obtained. The pre-exponential factors (A) were also determined as 7.67 × 1010 min−1 based on the F1 reaction model and FWO method. Implications: Municipal solid waste (MSW) is a complex mixture of different components and the plastic takes up a significant portion in total MSW. Understanding the combustion process of typical electronic plastic waste and further probing its combustion kinetic are significant. Through this study, it will be significant for the reactor designing and optimizing in practice.

Heteroleptic cadmium complex of glimepiride–metformin mixed ligand: synthesis, characterization, and antibacterial study

A heteroleptic cadmium complex was synthesized from two antidiabetic drugs, namely metformin and glimepiride, by a continuous stirring and reflux process. The metal–ligand binding was confirmed by their physicochemical and spectroscopic studies. The characterization of the complex was done by elemental microanalysis, FTIR, ESI–MS, electronic absorption spectral study, 1H and 13C-NMR, PXRD, SEM, M.Pt., pH, and conductivity measurements. The octahedral geometry was confirmed for the complex by spectral studies, and its nanocrystalline nature was confirmed from the meticulous analysis of PXRD peaks. The crystallinity of the complex was calculated to be 47.66%. The Coats–Redfern method was used to evaluate the thermodynamic and kinetic parameters, such as E*, ΔH*, ΔG*, and ΔS* from the TGA/DTA data. The surface morphology and particle size of the artifact metal complex were assured by scanning electron microscopy (SEM) study. Similarly, the nonelectrolytic nature of the complex was suggested based on its molar conductivity data. The complex was screened in vitro against some selected human pathogenic bacteria using the paper disk diffusion technique to validate antibacterial potency. The exact quantitative information for antibacterial potency was ensured by measuring minimum inhibitory concentration values. In this study, a remarkable antibiotic property of the complex was observed. Amikacin 30 µg/disk was used as a reference standard to compare antibacterial potency.

Facile fabrication of NiAl-LDH and its application in TPU nanocomposites targets for reducing fire hazards

ABSTRACT In this study, nickel-aluminium layered double hydroxide (NiAl-LDH) was prepared and characterised. NiAl-LDH was incorporated into thermoplastic polyurethane (TPU) to prepare a series of TPU/NiAl-LDH nanocomposites using solution mixing technology. Thermogravimetric analysis revealed that the addition of NiAl-LDH increased the thermal stability of TPU/NiAl-LDH nanocomposite at high temperatures. Kinetic analysis of the nanocomposites was conducted via the Coats–Redfern method. Thermogravimetric infrared spectroscopy was carried out to investigate gaseous pyrolysis products in degradation process of TPU/NiAl-LDH nanocomposites. TPU/NiAl-LDH nanocomposites showed a significant decrease in CO, hydrocarbon, and aromatic compound intensities than those of pure TPU, indicating that NiAl-LDH can effectively reduce the fire hazard associated with TPU nanocomposites. Furthermore, X-ray photoelectron spectroscopy, scanning electron microscopy, and Raman spectroscopy were used to analyse char residues of TPU/NiAl-LDH nanocomposites. TPU/NiAl-LDH nanocomposites produced a denser char layer with a significantly enhanced graphitisation degree, which inhibited substance and heat transfer during combustion.

Investigations on Mediterranean biomass pyrolysis ability by thermogravimetric analyses: thermal behaviour and sensitivity of kinetic parameters

A comparison of the thermal behaviours of different Mediterranean biomasses, based on the evaluation of their pyrolysis characteristic temperatures, their reactivity and kinetic parameters is presented. Parameters such as the activation energy and the pre-exponential factor of the pyrolysis reactions are determined by different methods (Kissinger, Kissinger–Akahira–Sunose [KAS], Coats–Redfern, nonlinear least-squares minimization [NLSM] and model distributed activation energy model [DAEM]). Furthermore, a sensitivity analysis of the kinetic parameters based on different methods is conducted. The comparison of this work with the literature, showed that thermal characteristic parameters determined using the thermogravimetric analysis (TGA) are often neglected and not used in biomass pyrolysis at laboratory scale. The kinetic parameters seem to be highly sensitive to the used kinetic methods. For a given biomass, such as the Aleppo pine husk residue, for example, the activation energy can vary from 65.80 to 197.08 kJ·mol -1 depending on the used method. For this biomass, the highest average activation energy (190 kJ·mol -1 ) was estimated by the KAS and DAEM methods. The Kissinger method yields to an activation energy close to that of cellulose calculated by the NLSM method. For all biomasses, the activation energy remains between 150 and 200 kJ·mol -1 except for the Coats–Redfern method, where this value is in the range of 50–100 kJ·mol -1 . Therefore, it is important to have a means of recommending the most appropriate method for the determination of kinetic parameters.

THERMAL BEHAVIOUR KINETIC MODELING OF CAPSICUM ANNUUM WASTE BIOMASS USING AN ISO-CONVERSION METHOD

In the present study, the pyrolysis behaviour of Capsicum Annuum stem Waste (CAW) was studied applying thermogravimetric analysis to evaluate the intrinsic kinetic parameters to develop a pyrolysis reactor for utilizing CAW. The thermal decomposition of CAW was achieved between 373 – 1173 K under inert conditions at different heating rates of 10, 20, and 30 K min-1. Model-free kinetic methods like Kissinger-Akahira-Sunose (KAS), Ozawa Flynn Wall (OFW) and Coats Redfern methods were applied to work out the kinetic parameters. To identify the utility of CAW and its biochar, physio-chemical characteristics such as proximate and ultimate analysis, scanning electron microscopy, and Fourier Transform Infrared analysis are reported.

Growth and characterization of organic material 3,4-dimethoxybenzaldehyde-2,4-dinitroaniline single crystal

The organic material 3,4-dimethoxybenzaldehyde-2,4-dinitroaniline was synthesised and the single crystal has been grown by slow evaporation technique. Single-crystal X-ray diffraction studies show that the grown 3,4-dimethoxybenzaldehyde-2,4-dinitroaniline single crystal belongs to the monoclinic system with the centrosymmetric space group P21/n. The FTIR and FT-Raman spectra were recorded to identify the functional groups present in the grown crystal. The optical property of the grown crystal was analyzed by UV–Vis–NIR studies and determines the optical band gap, the refractive index, the optical conductivity and the Urbach energy. The photoluminescence (PL) studies show that the grown crystal has green colour emission. The thermal property of the grown crystal was analysed by thermogravimetric (TG) and differential thermal analyses (DTA). The kinetic parameters such as the activation energy, frequency factor, entropy, enthalpy and Gibbs-free energy are computed from TGA data using Coats–Redfern method. The dielectric studies were analyzed by using the parallel plate capacitor method. The activation energy is calculated from Arrhenius plot. The electronic properties such as the plasma energy, the Penn gap, the Fermi energy and the electronic polarizability are calculated. The third order nonlinear optical properties of 3,4-dimethoxybenzaldehyde-2,4-dinitroaniline was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser.

Isoconversional analysis of kinetic pyrolysis of virgin polystyrene and its two real-world packaging wastes

In present work, two polystyrene packaging wastes of expanded polystyrene (EPS) foam and Yakult polystyrene milk bottle (YPS) along with pure polystyrene (PS) have been subjected to high-temperature nitrogen pyrolysis experiments under four heating rates of 5, 10, 15 and 20 K min−1. A comparison among these samples in terms of pyrolysis features and specific decomposition temperatures has been made, and EPS tends to be the most readily to undergo pyrolysis while YPS appears to be the most thermally stable. Based on thermogravimetric data, kinetic analysis has been systematically performed using various isoconversional methods. The calculations show that the activation energies calculated over the whole pyrolysis range are slightly different among the six temperature-integral methods, but the temperature-differential Friedman method has given rather distinct activation energies. The activation energies over the whole pyrolysis process are mass conversion-dependent for three samples and the activation energy averaged is the highest for YPS, followed by pure EPS and then EPS. A method combining master-plots method and differential composite method has been attempted to search the most suitable reaction models and chemical reaction order-based F0.58, F0.61 and F1.14 are found to be the most suitable reaction models for describing pyrolysis of PS, EPS and YPS, respectively. With the Coats–Redfern method, the mass-conversion curves along with its differential curves have been simulated, yielding very satisfactory performances for three polystyrene samples. In addition, thermodynamic functions such as the changes of entropy, enthalpy and Gibbs free energy during waste pyrolysis processes are also considered.

Combustion and Kinetics Parameters Investigation of Raw and Torrefied Cocoa Pod Shells by Thermogravimetric Analysis

Torrefaction is one of the techniques to produce solid fuel from cocoa pod shell (CPS). In this research, changing combustion characteristic and kinetics of CPS after torrefaction process was investigated using Coats – Redfern Method. Torrefied CPS processed at temperatures of 200, 250, and 300°C and holding times of 0, 30, 60, and 90 min were used in this investigation. The results proved that the ignition and burnout temperatures shifted to higher value, while the peak mass loss rate tend to lower value when the torrefaction temperature and the holding time increased. The period of volatile release during the combustion process was shorter along with longer holding time and higher temperature of torrefaction. The maximum mass loss rate of raw CPS was 0.12005 g/min, while torrefied CPS has range between 0.046 to 0.114 g/min. The maximum mass loss rates of all samples decrease with increasing fuel ratio (FR). The activation energy increases gradually with increasing severity of torrefaction. The value of activation energy in the devolatilization and volatile combustion stage is greater compared to that of the char combustion stage.

Investigation of kinetic decomposition characteristics of Malaysian wood species using Coats and Redfern (CR) method

The mass loss against temperature and time through thermogravimetry analysis (TGA) was measured upon six wood species: Shorea laevis (Balau), Vatica rassak (Resak), Koompassia malaccensis (Kempas), Heritiera albiflora (Mengkulang), Shorea parvifolia (Meranti sarang punai), and Cratoxylum arborescens (Geronggang) at the heating rates of 5, 10, and 20 °C/min in a nitrogen environment. These species have shown three stages of thermal decomposition, including the dehydration stage, the active stage, and the passive stage. The thermal decomposition curves exposed that the hemicellulose and cellulose were actively pyrolyzed during the second-stage of the pyrolysis (active stage). In contrast, the decomposition of lignin happens at a slower pace in both the second and third-stage (passive stage). The maximum decomposition peak in the derivative thermogravimetric (DTG) curves for every species moved to a higher temperature range following the acceleration in heating rates. The kinetic decomposition parameters of the woods were identified by embracing the thermal kinetic method of Coats and Redfern (CR). The higher activation energy (E a ) in the second-stage demonstrates that the corresponding species consists of more cellulose compared to others. Furthermore, all species showed lower E a during the third-stage of pyrolysis involving lignin content. The pre-exponential factor (A) for all species disclosed a relative connection to the E a ; the higher the E a , the higher the value of A.

Biological evaluation, molecular docking, DNA interaction and thermal studies of new bioactive metal complexes of 2‐hydroxybenzaldehyde and fluorobenzamine Schiff base ligand

Schiff base ligand named 2‐((E)‐(2‐fluorophenylimino)methyl)phenol (HL) was prepared by the condensation of 2‐hydroxybenzaldehyde and 2‐fluorobenzamine in 1:1 molar ratio. The coordination behaviour of a series of transition metal ions with the synthesized HL ligand, [Cr(HL)2] (1), [Fe(HL)2] (2), [Co(HL)2] (3) and [Cu(HL)2] (4) is reported. The structure and bonding of the metal complexes have been deduced by analytical and spectral studies. Based on the above studies, the metal centres were found to be octahedral for all the complexes. The activation thermodynamic properties were calculated using the Coats–Redfern method. Thermal decomposition processes of complexes 1, 2, 3 and 4 are non‐spontaneous; that is, the complexes are thermally stable. The positive value of Gibbs free energy of decomposition (ΔG*) for all the complexes is non‐spontaneous processes. DNA binding properties of these metal complexes, investigated using UV–visible absorption, fluorescence and viscosity measurement studies, imply that the complexes bind to DNA by intercalation. The intrinsic binding constant Kb from the electronic absorption studies are 3.12 × 104 M−1, 1.86 × 104 M−1, 3.96 × 104 M−1 and 5.89 × 104 M−1, and the Stern–Volmer quenching constant Ksv values from fluorescence studies are 2.29 × 104 M−1, 1.92 × 104 M−1, 5.62 × 104 M−1 and 8.91 × 104 M−1, for the complexes 1, 2, 3 and 4, respectively. DNA photo cleavage activities of these complexes were studied with supercoiled pUC19 DNA, in the presence of H2O2. GOLD 3.1 program was used to evaluate binding affinities of complexes with human DNA topoisomerase I protein. in vitro cytotoxic and antimicrobial studies revealed higher activity of metal complexes, compared with the ligand.

Elucidation of Thermal Degradation Model for Low and High Density Polyethylene by Statistical Parameters

AbstractSolid state decomposition studies of Low and High Density Polyethylene (LDPE and HDPE) have been carried out in the present work. Thermo‐gravimetric analysis (TGA) is utilized to determine the degradation kinetics for pure plastic samples at different heating rates. The distribution of activation energy values and rates estimated using various Iso‐conversional methods have been selected on basis of correlation coefficients. For LDPE, isoconversional method of Friedman and for HDPE Flynn Wall Ozawa methods are used to estimate the distribution of activation energies having their mean values as 256.5 and 257.2 kJ/mol respectively. The inputs from Isoconversional methods are used to determine decomposition behavior with Criado method. Model based studies performed with Criado method identifies the solid‐state degradation follows contracting volume‐sphere (R3) model based on lower statistical parameter values. The identified decomposition model is validated by Coats Redfern method which also results in lower statistical parameter values. This is further validated through a best fit of extent of reaction profile against temperature, substantiating the solid‐state decomposition model followed by given plastic fractions.

Pyrolysis Kinetic Study and Reaction Mechanism of Epoxy Glass Fiber Reinforced Plastic by Thermogravimetric Analyzer (TG) and TG-FTIR (Fourier-Transform Infrared) Techniques.

TG–FTIR combined technology was used to study the degradation process and gas phase products of epoxy glass fiber reinforced plastic (glass fiber reinforced plastic) under the atmospheres of high purity nitrogen. The pyrolysis characteristics of epoxy glass fiber reinforced plastic were measured under different heating rates (5, 10, 15, 20 °C min−1) from 25 to 1000 °C. The thermogravimetric analyzer (TG) and differential thermogravimetric analyzer (DTG) curves show that the initial temperature, terminal temperature, and temperature of maximum weight loss rate in the pyrolysis reaction phase all move towards high temperature, as the heating rate increases. Epoxy glass fiber reinforced plastic has two stages of thermal weightlessness. The temperature range of the first stage of weight loss is 290–460 °C. The second stage is 460–1000 °C. The above two weight loss stages are caused by pyrolysis of the epoxy resin matrix, and the glass fiber will not decompose. The dynamic parameters of glass fiber reinforced plastic were obtained through the Kissinger-Akahira-Sunose (KAS), Flynn–Wall-Ozawa (FWO) and advanced Vyazovkin methods in model-free and the Coats–Redfern (CR) method in model fitting. FTIR spectrum result shows that the main components of the product gas are CO2, H2O, carbonyl components, and aromatic components during its pyrolysis.

Radiographic Reference Points Do Not Ensure Anatomic Femoral Fixation Sites in Medial Patellofemoral Ligament Reconstruction: A Quantified Anatomic Localization Method Based on the Saddle Sulcus

Background: Medial patellofemoral ligament (MPFL) reconstruction is one of the main treatments for lateral patellar translation. Based on intraoperative true lateral radiographs, the accepted methods for femoral MPFL tunnel location are potentially inaccurate. Direct assessment of anatomic characteristics during surgery through palpation of the anatomic landmarks involving the saddle sulcus might help eliminate tunnel malposition. Hypothesis: The saddle sulcus is a reliable osseous landmark where the MPFL attaches for tunnel placement. Study Design: Descriptive laboratory study. Methods: A total of 9 fresh-frozen unpaired human cadaveric knees were dissected; MPFL insertion point and relative osseous structures were marked. Three-dimensional images and transformed true lateral radiographs were obtained for analysis; 3 previously reported radiographic reference points for MPFL femoral tunnel placement were determined on all images and compared with the anatomic insertion. Results: A saddle sulcus consistently existed where the MPFL was attached, located at 11.7 ± 5.9 mm from the apex of the adductor tubercle (AT) to the medial epicondyle (ME), 62.8% of the average distance between the apexes of the AT and ME, and 5.6 ± 2.8 mm perpendicular-posterior to the border connecting the AT and ME. The reported radiographic reference points were located at average distances of 6.2 ± 3.2 mm (Schöttle method), 5.9 ± 2.3 mm (Redfern method), and 7.3 ± 6.6 mm (Fujino method) from the saddle sulcus center on the true lateral radiographs. Conclusion: The saddle sulcus was a reliable landmark where the MPFL was anatomically attached, located approximately 12 mm from the AT to the ME (approximately 60% along a line from the AT to the ME) and 6 mm perpendicular-posterior to the border connecting the apexes of the AT and ME. Additionally, the saddle sulcus position presented variability on the femoral aspect of different knees. All of the average direct distances from the sulcus to the reference radiographic points exceeded 5 mm, and tunnel localizations on a true lateral radiograph were inaccurate. Clinical Relevance: This study demonstrates the potential precise position of the saddle sulcus, according to the ME and AT, as a reliable anatomic landmark for MPFL femoral tunnel location. Radiographic reference points were not accurate during MPFL reconstruction. Direct palpation of the landmarks might be effective for femoral MPFL tunnel placement.