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Straw Degradation Behaviors under Different Conditions of Relative Air Humidity and Ultraviolet-A Irradiation
摘要： In this study, straw was degraded continuously for 150 days under one of three levels of relative air humidity (RH) (90%, 60%, or 30%) to estimate the effect of humidity on straw biodegradation. Moreover, straw was treated with ultraviolet (UV)-A irradiation + 90% RH for 180 days to evaluate the interaction between photodegradation and biodegradation. The effects of 30% and 60% RH on straw degradation was inconspicuous. Straw mass losses at 90% RH and UV-A + 90% RH were 18.5% and 39.1%, respectively. BIOLOG analysis showed that filamentous fungi played a major role in straw biodegradation. Thermogravimetric analysis showed that treatment with UV-A + 90% RH tended to increase the maximum pyrolysis rate and decreased the initial pyrolysis temperature. Compared with 90% RH, infrared spectra analysis showed that functional groups of UV-A + 90% RH treatment, e.g., –CH, –C=O, and the benzene ring structure, clearly decreased. Straw-degrading bacteria were observed by scanning electron microscopy at the beginning and end of UV-A + 90% RH treatment. Results highlight the role of humidity in the degree of straw biodegradation by filamentous fungi. Straw degradation is accelerated by the combined action of photodegradation and biodegradation under high UV-A irradiation and high humidity.
关键词： Relative air humidity,Biodegradation,TGA,Photodegradation,Ultraviolet-A irradiation,BIOLOG,SEM,ATR-FTIR
更新于2025-09-23 15:23:52
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Synthesis and characterization of novel imine substituted phthalocyanine for sensing of l-cysteine
摘要： New mono-nuclear cobalt (II) tetra[4-(2-{(E)-[(4-bromophenyl)imino]methyl}phenoxy)] phthalocyanine (CoTBrImPc) complex has been synthesized for the first time in pure state. The synthesized dark blue coloured complex was characterized by elemental analysis, IR, UV-Vis, NMR, Mass, powder X-ray diffraction and thermogravimetric analysis (TGA) to understand the structural integrity, purity and crystalline property of the complex. The synthesized phthalocyanine complex was found to be electrochemically active and it was immobilized on the glassy carbon electrode by drop-casting method and used for the detection of L-cysteine. The CoTBrImPc modified electrode was found to be a good electrocatalyst for the catalytic oxidation of L-cysteine with shift in the overpotential towards less positive potential and an increase in the catalytic current compared to bare glassy carbon electrode (GCE). The linear response was observed for the voltametric detection of L-cysteine in the concentration range 10-100 nM with coefficient of regression R2= 0.9993 and LOD of 3 nM and sensitivity of 2.99 μA nM-1 cm-2. The amperometric sensor was also developed for the detection of L-cysteine which showed linear response in the concentration range same as that of cyclic voltammertry technique with a linear equation y = 0.7582x+16.9535 and correlation coefficient of R2= 0.9961. The LOD and LOQ values for amperometric detection were 4 nM and 12 nM, respectively with the sensitivity value of 10.81 μA nM cm-2.
关键词： TGA,L-cysteine,XRD,Amperometry.,Phthalocyanine,cyclic voltammetry
更新于2025-09-23 15:23:52
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Thermal oxidative decomposition estimation combining TGA and DSC as optimization targets for PMMA
摘要： Thermal analysis techniques play a key role to determine and characterize solid phase thermal decomposition. In this sense, Simultaneous Thermal Analysis (STA, i.e. TGA and DSC tests carried out simultaneously) are widely employed, since it provides information about how mass is lost and energy released while the temperature of the sample increases. Fire computer models combined with methods numerical methods are widely used to represent the results from tests and to achieve the values of the kinetic and thermal parameters. Previous works looked forward achieving those parameters using, as unique optimization target, the mass loss curve (TGA) or its derivative (DTGA). As the study of heat release rate is a decisive element to characterize the material properly, most recent works were adding additional measures. These extra measurements concern the heat transfer and the energy required or released during temperature programmed heating, such as heat rate release, heat of gasification, or the surface temperatures of the samples. The information about the energy is provided by the Differential Scanning Calorimetry curve (DSC). Despite of the employment of the information provided by the DSC, this information usually is not used as a target to approach the DSC simulated curve to the experimental one as TGA does. Based on the lack of use of the DSC curve as numerical approaching process to set the kinetic properties, we decide to explore the possibility of adding this as a new target in the process. Therefore, kinetic and thermal properties might be achieved fitting experimental and simulated curves simultaneously, which should allow us to take into account the decomposition process and their energy released. Results obtained in the present work reveal the major challenge of getting a set of parameters, which can fit DSC curve. The level of accuracy reached when only TGA is utilized as target to approach is higher than the level of accuracy of DSC curve. This fact makes increase the value of the errors when both curves are used as targets to approach. In other words, an approach to both curves simultaneously cannot be directly made. With this consideration in mind, this paper proposes an alternative methodology in order to fit TGA curve considering the optimization of the DSC curve. The methodology proposed in the present work is applied to the analysis of poly(methyl methacrylate) (PMMA).
关键词： DSC,numerical methods,TGA,CFD,Thermal decomposition,PMMA,optimization methods,solid phase chemistry
更新于2025-09-23 15:23:52
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Microstructural interpretation of charge transport dynamics of chemically derived ZnCo2O4 under mechanical milling
摘要： In this work, milling effect on chemically synthesized nanocrystalline Zinc Cobaltite (ZnCo2O4) has been investigated and we report how the structural and electrical properties vary with the milling span. Phase pure ZnCo2O4 has been successfully synthesized via simple and cost-effective co-precipitation method and then it has been milled for one, four and eight hours respectively. XRD confirms formation of single phase cubic structure for both milled and unmilled nano-powders. Different microstructural parameters has been estimated from Rietveld analysis, which shows particle size reduction from ~29.64 nm for unmilled sample to ~18.13 nm for eight hour milled sample. TGA-DSC curve of as prepared sample shows good temperature stability that helps to estimate the appropriate sintering temperature for the samples. TEM analysis also gives values of grain size in agreement with Reitveld analysis. Frequency dependent ac conductivity curve obeys universal Jonscher power law and temperature dependence of frequency exponent is explained by small polaron transaction. Comparable activation energies from hopping mechanism and relaxation process indicates similar transport mechanism. Superimposed scaling spectra obeys TTSP principle. AC conductivity increases with frequency as a result of hopping of the charge carriers. Smaller particles with reduced strain gives enhanced conductivity as well as enhanced value of hopping frequency. This further suggests creation of excess charge carriers in milled samples. Cole-Cole plot shows non-Debye type behavior of the samples. The dielectric loss factor increases with lowering of particle size since smaller grains contributes to faster charge conduction.
关键词： TGA-DSC,Mechanical milling,Electrical characterisation,dielectric loss factor,Microstructure
更新于2025-09-23 15:22:29
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Novel report on structural, optical and electrical investigation into brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate single crystal: a promising material for high-power laser, ultrahigh cooling, sensor and detector applications
摘要： A new brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate (B4M3NB0.5H) NLO single crystal was harvested from saturated solution by solvent evaporation method. Crystal system and symmetric type of B4M3NB0.5H compound were analyzed by structure analysis. Linear optical parameters of title compound were discussed in detail by UV–visible analysis. Lifetime values of the molecule were quanti?ed by ?uorescence study, and it con?rms the good crystalline perfection of the grown crystal. The SHG ef?ciency is 5.11 times superior to the KDP material. By utilizing Nd:YAG laser as an input, SLDT measurement of the crystal was done. The grown crystal has good crystalline nature which is analyzed by HRXRD study. Dielectric behavior of B4M3NB0.5H crystal was discussed in detail. With the help of theoretical approach, few of the solid-state parameters were calculated and listed. Piezoelectric charge coef?cient and piezovoltage were calculated to be 4.5 p C/N and 0.0417 p V m/N, respectively. The TGA and DTA spectrum con?rms that the title compound is thermally stable up to 101 °C.
关键词： piezoelectric charge coefficient,brucinium 4-methyl-3-nitrobenzoate,fluorescence study,solvent evaporation method,SHG efficiency,HRXRD study,NLO single crystal,Nd:YAG laser,dielectric behavior,UV–visible analysis,TGA and DTA spectrum
更新于2025-09-23 15:21:01
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Laser-Induced Voltage of Oil Shale during Retorting
摘要： In this study, a 248 nm laser was used to analyze oil shale at di?erent pyrolysis temperatures. An induced voltage was obtained when the ultraviolet laser irradiated the oil shale surface. The laser-induced voltage (LIV) peak decreases with temperatures below 200 °C, increases with temperatures in the range 200?400 °C, and then decreases above 400 °C. The critical temperatures of 200 and 400 °C corresponded well with the points conformed using thermogravimetry and di?erential scanning calorimetry (TGA-DSC), gas chromatography and gas chromatography coupled (TG-FTIR-MS), and scanning electron microscopy (SEM). Our research suggested that an LIV method could be applied to the analysis of the oil shale pyrolysis process.
关键词： oil shale,TGA-DSC,TG-FTIR-MS,pyrolysis,laser-induced voltage,SEM
更新于2025-09-23 15:19:57
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Unprecedented surface stabilized InP quantum dots with bidentate ligands
摘要： For InP-based QDs, the current technology does not outperform CdSe-based QDs in many respects, one of which is stability. The optical stability of QDs is closely related to their surface properties, so QDs often use organic ligands for surface protection. These organic ligands are dynamically attached and detached on the QD surface; during detachment, their surfaces are easily damaged and oxidized, thereby deteriorating their optical characteristics. Therefore, we have synthesized a ligand 1,2-hexadecanedithiol with a bidentate form, inducing one ligand to bind to the QD surface strongly through the chelate effect, as a good way to improve the stability of the QDs; thus, the PL stability of the green-light-emitting InP-based QDs was greatly increased. To confirm the existence of the dithiol ligand, we used thermogravimetric analysis/simultaneous thermal analysis-mass spectroscopy (TGA/STA-MS). After that, we applied the ligand to blue-light-emitting ZnSe QDs and red-light-emitting InP QDs, and for those two types of QD we also confirmed that the stability was increased. Additionally, we tested dithiol exchanged QDs at a high temperature of 150 °C, and the increase of stability was effective even in a high temperature condition.
关键词： stability,quantum dots,bidentate ligands,InP-based QDs,TGA/STA-MS
更新于2025-09-23 15:19:57
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Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces
摘要： The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag2S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν(S ? H) TGA peak (2559 cm?1) disappears in FTIR spectra of Ag2S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag2S nanocrystals. Ag2S QDs passivation with TGA molecules leads to emergence νas(COO?) (1584 cm?1) and νs(COO?) (1387 cm?1) peaks. It indicates TGA adsorption in ionic form. For Ag2S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of νs(COO?) peak from 1388 cm?1 to 1359 cm?1 and high-frequency shift of νas(COO?) peak from 1567 cm?1 to 1581 cm?1; (b) change in the ratio of intensities of νas(COO?) and νs(COO?) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag2S quantum dots.For Ag2S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm?1 for νas (COO?) at 1567 cm?1 and low-frequency shift of 3–5 cm?1 for νs (COO?) at 1388 cm?1, probably caused by the interaction of thiol with Ag2S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag2S QDs. In the case of Ag2S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α-thiol-substituted acyl radical (S-CH2-CO?) TGA.
关键词： photodegradation,FTIR spectra,thioglycolic acid (TGA),dimer,luminescence,Ag2S quantum dots,ionic form
更新于2025-09-23 15:19:57
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Synthesis and Characterization of Substituted Metal(II)-octa- MethoxyphenylImino Phthalocyanine Pigments
摘要： The synthesis, spectral and magnetic susceptibility on symmetrically substituted metal(II)-octa-methoxyphenyl imino phthalocyanine by condensing octa amino phthalocyanines with o-anisaldehyde are described. The dark green colour octa amino phthalocyanine derivatives were characterized by electronic, IR, elemental analysis, magnetic susceptibility, powder X-ray diffraction and thermo gravimetric analysis (TGA) studies to structural integrity, check the purity and crystalline properties of the pigments. The variation of magnetic moment as function of field strength 2.20 to 4.01 kg indicated the presence of intermolecular co-operative effect
关键词： TGA,Magnetic susceptibility,IR,Electronic,XRD,Octamethoxy imino phathalocynaine
更新于2025-09-19 17:15:36
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Structural characterization and thermal degradation of poly(methylmethacrylate)/zinc oxide nanocomposites
摘要： This work is based on the preparation of composites of poly(methylmethacrylate) with zinc oxide nanoparticles synthesized by solution casting method. Chloroform cast poly(methylmethacrylate) films containing different amounts of ZnO nanoparticles were characterized by XRD, SEM, UV-vis spectroscopy, FTIR spectroscopy and TGA. The results show that ZnO nanoparticles with a size of 24 nm were fairly dispersed in the polymer matrix. The obtained material had UV shielding capability with optical transparency. Thermal characterization shows that, the nanocomposites were more thermally stable than pure PMMA presenting three degradation steps. Apparent kinetic parameters were determined for each degradation step using peak fitting methodology. According to activation energies, ZnO particles affect simultaneously but oppositely the kinetics of underlying degradation reactions. Thermal stability of the PMMA/ZnO nanocomposites was the result of the overall balance in favor of the inhibiting effect of ZnO.
关键词： PMMA,polymer nanocomposites,activation energy,ZnO nanoparticles,degradation kinetics,TGA
更新于2025-09-19 17:15:36