Articles de revues : « Thermic and spectroscopic technique »

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K, Niyati. « Thermal Lens Technique as a Potential Optical Tool ». International Journal for Research in Applied Science and Engineering Technology 9, n^o 11 (30 novembre 2021) : 918–23. http://dx.doi.org/10.22214/ijraset.2021.38878.

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Abstract: The spectroscopic characterization of materials involves the use of various optical tools. Spectrometers, interferometers etc, are some of the examples of optical tools. Thermal lens technique is one of the potential optical tools for the thermal characterization of different materials. The thermal lens effect is a photothermal effect which results when energy from a laser beam is absorbed by a sample, causing heating of the sample along the beam path. In this paper an overview of thermal lensing, its significance as potential optical tool and its applications are discussed. Index Terms: Optical tool, Photothermal spectroscopy, TLS application, Thermal diffusivity

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Halenka, J., et H. Janus. « An Efficient Spectroscopic Control — Technique of the Parameters of Thermic Plasmas Produced under the Condition of a Variable Current ». Beiträge aus der Plasmaphysik 26, n^o 1 (1986) : 53–56. http://dx.doi.org/10.1002/ctpp.19860260107.

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Alrooqi, Arwa, Zahra M. Al-Amshany, Laila M. Al-Harbi, Tariq A. Altalhi, Moamen S. Refat, Ali M. Hassanien, Gaber A. M. Mersal et Ahmed A. Atta. « Spectroscopic and Physicochemical Studies on 1,2,4-Triazine Derivative ». Coatings 12, n^o 5 (23 mai 2022) : 714. http://dx.doi.org/10.3390/coatings12050714.

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A novel 5-(5-Bromo-2-hydroxybenzylidene)-6-oxo-3-phenyl-5,6-dihydro-1,2,4-triazine-2(1H)-carbothioamide (4) “compound 4” was synthesized. The chemical structure of compound 4 was confirmed with spectroscopic techniques. Thermal analysis (TGA/dTGA) studies were conducted for identifying the kinetic thermodynamic parameters and the thermal stability of the synthesized compound 4. Cyclic voltammetric studies were performed for recognizing electrochemical characteristics of the synthesized compound 4. The calculated highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and the band gap were found to be −3.61, −5.32, and 1.97 eV, respectively. Using a diffused reflectance spectroscopy (DRS) technique, the estimated values of the optical band transitions of compound 4 in powder form were found to be 2.07 and 2.67 eV. The structural properties of thermally evaporated compound 4 thin films were analyzed using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. It was found that compound 4 has a triclinic crystal structure. The optical transitions and the optical dispersion factors of compound 4 thin films were investigated using a UV-Vis spectroscopy technique. From the UV-Vis spectroscopy technique, Egind=3.6 V was estimated for both the as-deposited and annealed thin films. For the as-deposited film, there were two photoluminescence (PL) emission peaks centered at 473 and 490 nm with a shoulder at 422 nm. For the annealed film at 423 K, there were five PL emission peaks centered at 274, 416, 439, 464, and 707 nm with a shoulder at 548 nm. The dark electrical conduction of compound 4 thin film was through a thermally activated process with activation energy equaling 0.88 eV.

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Garces, Viviana, Angélica García-Quintero, Tulio A. Lerma, Manuel Palencia, Enrique M. Combatt et Álvaro A. Arrieta. « Characterization of Cassava Starch and Its Structural Changes Resulting of Thermal Stress by Functionally-Enhanced Derivative Spectroscopy (FEDS) ». Polysaccharides 2, n^o 4 (3 novembre 2021) : 866–77. http://dx.doi.org/10.3390/polysaccharides2040052.

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Starch is one of the biopolymers that has been recognized as promising for its application as an eco-friendly substitute for conventional polymers due to its biodegradable nature, low cost, and considerable abundance from renewable vegetal-type resources. In particular, the use of cassava starch as raw material in the manufacture of packaging materials has increased in recent years. Consequently, the analytical study of the quality and features of starch and its derivatives throughout their entire life cycle have gained importance, with non-destructive sample methods being of particular interest. Among these, spectroscopic methods stand out. The aim of this study was evaluated using spectroscopic techniques (i.e., mid-infrared spectroscopy (MIRS) and functional-enhanced derivative spectroscopy (FEDS)) for the monitoring of the effect of the thermal stress of starch in conjunction with computational tools such as density-functional theory (DFT). It is concluded that the FEDS technique in conjunction with DFT calculations can be a useful tool for the high-precision spectral analysis of polymers subjected to small thermal perturbations. In addition, it is demonstrated that small changes produced by thermal stress can be monitored by infrared spectroscopy in conjunction with FEDS at wavenumber range between 3800 and 3000 cm−1, which would allow for the implementation of spectral techniques instead of thermal techniques for out-lab evaluations and for the study of the thermal stress of biomaterials.

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Thomas, R. L., et L. D. Favro. « From Photoacoustic Microscopy to Thermal-Wave Imaging ». MRS Bulletin 21, n^o 10 (octobre 1996) : 47–52. http://dx.doi.org/10.1557/s088376940003164x.

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Photoacoustic spectroscopy is a technique in which the absorption of periodically intensity-modulated light is detected by the sound that it produces at the (acoustic) modulation frequency in a closed volume of gas or liquid in thermal contact with the material absorbing the light. The spectroscopic aspect of the technique relies on the ability to scan the wavelength of the light that stimulates the sound. Thus one can determine the absorption as a function of wavelength through the conversion of absorbed energy to heat and thence to sound. The acoustic detection is carried out synchronously with respect to the imposed intensity-modulation frequency on the light, making it possible to use narrow-band noise reduction. The existence of this technique for detecting sound generated by the absorption of light led Wong and co-workers to investigate the possibility of using the same techniques for microscopy.

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Caccamo, Maria T., et Antonio Cannuli. « PEG Acoustic Levitation Treatment for Historic Wood Preservation Investigated by Means of FTIR Spectroscopy and Wavelets ». Current Chemical Biology 13, n^o 1 (8 février 2019) : 60–72. http://dx.doi.org/10.2174/2212796812666180511115839.

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Background: The combination of Fourier Transform InfraRed and levitation techniques, both on levitated water mixtures of Polyethylene Glycols (PEG)s and on wood finds, allows to follow the polymeric drying process as a function of time through the O-H and C-H stretching contributions and to investigate the wood thermal response. Objective: The aim of this paper is to report the FTIR investigations on wood fines, extracted from a 700’ dated wooden crucifix. Methods: At first, different acoustically levitated Polyethylene Glycol (PEG) aqueous solutions were investigated by FTIR in order to characterize the levitation induced dehydration process; then the wood fines, after having been treated by immerging them into the PEG aqueous solutions, were acoustically levitated and investigated; finally the treated fines were again studied by IR spectroscopy through a thermic cycle in the 25 ÷ 350 °C temperature range. Levitation technique furnishes an innovative approach to sample treatment allowing, in the case of solutions, to obtain highly concentrated mixtures starting from diluted solutions while, in the case of wood find treatments, to increase the polymer solution penetration within the wood matrix. Results: It clearly emerges that, in the PEG200/PEG600 comparison, the lighter polymer shows a higher effectiveness in terms of thermal restraint. Conclusion: Acoustic levitation, in combination with IR spectroscopy, reveals to be a very powerful technique in many applications concerning wood preservation and conservation. It clearly emerges that, in the comparison with PEG600, PEG200 shows a higher effectiveness in terms of thermal restraint.

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Li, Bingcheng, Yanzhuo Deng et Jieke Cheng. « Pulsed Photothermal Deflection Spectroscopy with Optically Dense Samples ». Applied Spectroscopy 49, n^o 3 (mars 1995) : 279–85. http://dx.doi.org/10.1366/0003702953963436.

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The pulsed photothermal deflection spectroscopy (PTDS) method to determine the large optical absorption coefficient from the transverse PTDS magnitude and to measure spectroscopic data of optically dense sample from the normal-to-transverse magnitude ratio of the PTDS signal is presented and has been examined both theoretically and experimentally. Saturation at high absorption, effects of thermal inhomogeneity of the sample, and energy or power fluctuation of both the excitation and probe beams are avoided by this method. Together with the transverse PTDS technique, the dynamic range of spectroscopic measurement is over 9 to 10 orders of magnitude. This technique can be used with sample which is transparent or semitransparent to the probe beam.

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Hassoun, Abdo, Karsten Heia, Stein-Kato Lindberg et Heidi Nilsen. « Spectroscopic Techniques for Monitoring Thermal Treatments in Fish and Other Seafood : A Review of Recent Developments and Applications ». Foods 9, n^o 6 (10 juin 2020) : 767. http://dx.doi.org/10.3390/foods9060767.

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Cooking is an important processing method, that has been used since ancient times in order to both ensure microbiological safety and give desired organoleptic properties to the cooked food. Fish and other seafood products are highly sensitive to thermal treatments and the application of severe heat can result in negative consequences on sensory and nutritional parameters, as well as other quality attributes of the thermally processed products. To avoid such undesired effects and to extend the shelf life of these perishable products, both the heat processing methods and the assessment techniques used to monitor the process should be optimized. In this review paper, the most common cooking methods and some innovative ones will first be presented with a brief discussion of their impact on seafood quality. The main methods used for monitoring heat treatments will then be reviewed with a special focus on spectroscopic techniques, which are known to be rapid and non-destructive methods compared to traditional approaches. Finally, viewpoints of the current challenges will be discussed and possible directions for future applications and research will be suggested. The literature presented in this review clearly demonstrates the potential of spectroscopic techniques, coupled with chemometric tools, for online monitoring of heat-induced changes resulting from the application of thermal treatments of seafood. The use of fluorescence hyperspectral imaging is especially promising, as the technique combines the merits of both fluorescence spectroscopy (high sensitivity and selectivity) and hyperspectral imaging (spatial dimension). With further research and investigation, the few current limitations of monitoring thermal treatments by spectroscopy can be addressed, thus enabling the use of spectroscopic techniques as a routine tool in the seafood industry.

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Kwietniewski, N., Krystyna Gołaszewska, T. T. Piotrowski, W. Rzodkiewicz, Tomasz Gutt, M. Sochacki, Jan Szmidt et Anna Piotrowska. « Oxidation Process of SiC by RTP Technique ». Materials Science Forum 615-617 (mars 2009) : 529–32. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.529.

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The kinetics of 4H-SiC thermal oxidation by RTP technique and the properties of thin thermal oxide was reported. The thickness of the thermal oxide was determined by spectroscopic ellipsometry and confirmed by electrical measurements. The conductance method was applied to analyse the surface states parameters. The lifetime, density and cross-section of the surface traps were extracted for as-fabricated MOS capacitors and after thermal annealing processes.

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Thomas, Jeena, Prakash Perikaruppan, Vinoy Thomas, Jancy John, Raji Mary Mathew, Joice Thomas, Ibrahimkutty Rejeena, Sebastian Mathew et Abdulhassan Mujeeb. « Green Synthesized Plasmonic Silver Systems for Potential Non-Linear Optical Applications : Optical Limiting and Dual Beam Mode Matched Thermal Lensing ». Australian Journal of Chemistry 72, n^o 6 (2019) : 460. http://dx.doi.org/10.1071/ch18617.

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Bioactive compound functionalized plasmonic systems are evolving as a promising branch of nanotechnology. In this communication the synthesis of bioactive compound mimosine-based silver nanoparticles (AgNPs) and their non-linear optical and thermo-optic properties are presented. UV-Visible spectroscopy, optical bandgap measurement, fluorescence spectroscopy, and high-resolution transmission electron microscopy (HRTEM) techniques were used to characterize the synthesized AgNPs. An open aperture z-scan technique was used to determine the non-linear optical parameters. A very strong reverse saturable absorption (RSA) and low optical limiting threshold were observed for the present mimosine decorated AgNP system. The thermo-optic property of the present system was evaluated using a highly sensitive dual beam mode matched thermal lensing spectroscopic technique. A comparison of the low limiting threshold (242MWcm−2) and thermo-optic property (thermal diffusivity, D=1.13×10−7m2s−1) with similar systems proves its capability for non-linear optical and thermo-optic applications.

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Krstić, Marko, et Slavica Ražić. « Analytical Approaches to the Characterization of Solid Drug Delivery Systems with Porous Adsorbent Carriers ». Current Medicinal Chemistry 25, n^o 33 (24 octobre 2018) : 3956–72. http://dx.doi.org/10.2174/0929867325666180212120908.

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A large variety of analytical techniques are available to meet the needs of characterization of solid samples. But, when solid drug delivery systems are concerned we are faced with demanding methodologies which have to compile capabilities of analytical techniques in regard to large diversity of structures and surface functionality of analyzed adsorbent carriers. In this review, the most commonly used analytical techniques are presented with their basic principles, advantages and disadvantages in applications of interest. Adsorbent carriers are widely used today as ingredients in the formulation of pharmaceutical forms, for increasing the dissolution rate of the drug and hence the bioavailability. They are also used in the formulation of substances with modified or target drug release into a specific tissue. Methods of thermal analysis (Thermogravimetry - TGA, Differential Scanning Calorimetry - DSC and Thermal microscopy - TM), spectroscopic methods (Infrared Spectroscopy - IR, especially Fourier Transform Infrared Spectroscopy - FTIR and Raman spectroscopy), crystallographic methods (Powder X-Ray Diffraction - PXRD) and finally Scanning Electron Microscopy (SEM) are the most powerful in the characterization of modern therapeutic systems with porous adsorbents. The problem-solving power of each particular analytical method is often enhanced by using simultaneous methods rather than a single technique.

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Perinelli, Diego Romano, Marco Cespi, Giovanni Filippo Palmieri, Annalisa Aluigi et Giulia Bonacucina. « High-Resolution Ultrasound Spectroscopy for the Determination of Phospholipid Transitions in Liposomal Dispersions ». Pharmaceutics 14, n^o 3 (18 mars 2022) : 668. http://dx.doi.org/10.3390/pharmaceutics14030668.

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High-resolution ultrasound spectroscopy (HR-US) is a spectroscopic technique using ultrasound waves at high frequencies to investigate the structural properties of dispersed materials. This technique is able to monitor the variation of ultrasound parameters (sound speed and attenuation) due to the interaction of ultrasound waves with samples as a function of temperature and concentration. Despite being employed for the characterization of several colloidal systems, there is a lack in the literature regarding the comparison between the potential of HR-US for the determination of phospholipid thermal transitions and that of other common techniques both for loaded or unloaded liposomes. Thermal transitions of liposomes composed of pure phospholipids (dimyristoylphosphatidylcholine, DMPC; dipalmitoylphosphatidylcholine, DPPC and distearoylphosphatidylcholine, DSPC), cholesterol and their mixtures were investigated by HR-US in comparison to the most commonly employed microcalorimetry (mDSC) and dynamic light scattering (DLS). Moreover, tramadol hydrochloride, caffeine or miconazole nitrate as model drugs were loaded in DPPC liposomes to study the effect of their incorporation on thermal properties of a phospholipid bilayer. HR-US provided the determination of phospholipid sol-gel transition temperatures from both attenuation and sound speed that are comparable to those calculated by mDSC and DLS techniques for all analysed liposomal dispersions, both loaded and unloaded. Therefore, HR-US is proposed here as an alternative technique to determine the transition temperature of phospholipid membrane in liposomes.

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Marcott, Curtis, et Robert C. Reeder. « Infrared spectroscopic chemical imaging ». Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 août 1996) : 260–61. http://dx.doi.org/10.1017/s0424820100163769.

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Infrared (IR) spectroscopy is a powerful, widely used technique for identifying materials or chemical compounds. An IR spectrum often provides a specific fingerprint for a given molecular component or species. IR frequencies, intensities, and line widths are also extremely sensitive to environmental perturbations and changes in molecular structure. Infrared spectroscopic images recorded through a Fourier transform infrared (FT-IR) microscope attachment have traditionally been constructed by translating a mapping stage a single pixel at a time through the sample area of interest; this is a very tedious and time-consuming procedure. Recently, a technique for rapidly performing high-fidelity FT-IR imaging spectroscopy using an indium antimonide (InSb) focal-plane array (FPA) detector coupled to an IR microscope and a step-scanning FT-IR spectrometer has been developed. These multichannel IR detectors were originally developed for thermal-imaging applications (mainly in the military), but they have tremendous potential as chemical imaging detectors when used as part of a spectrometer. The multiple detector elements enable images from all pixels to be collected simultaneously for each mirror retardation position of the interferometer. Use of an interferometer allows the entire IR spectrum over some wavelength range to be measured. The combination of a step-scanning FT-IR microscope and an InSb FPA detector provides unprecedented speed and image quality, limited only by the diffraction limit and/or the number of detector elements on the array.

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Gokul, Vijayakumar, Mohanachandran Nair Sindhu Swapna, Dorota Korte et Sankaranarayana Iyer Sankararaman. « Reflecting the Quality Degradation of Engine Oil by the Thermal Diffusivity : Radiative and Nonradiative Analyses ». Materials 16, n^o 2 (12 janvier 2023) : 773. http://dx.doi.org/10.3390/ma16020773.

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Ageing of engine oil is an important issue determining the engine life and performance. The present work attempts to delineate the ageing-induced changes in engine oil through the mode-mismatched dual-beam thermal lens (MMDBTL) technique and other conventional spectroscopic techniques. For the analyses, engine oil samples were collected after every 200 km of runtime. As the thermal diffusivity is related to the nonradiative deexcitation upon optical absorption, comprehensive radiative and nonradiative analyses were carried out. The Ultraviolet-Visible, Fourier transform infrared, and Nuclear magnetic resonance spectroscopic analyses point to the structural modification as a result of the breaking of the long-chain hydrocarbons into ketones, aldehydes, esters, and other compounds. This modifies the absorption pattern, which can also be understood from the nonlinear refractive index study using the Z-scan technique. The compositional variations associated with the degradation upon ageing, the length of the hydrocarbon chain, and the formation of newer molecules account for the enhancement of the thermal diffusivity revealed through the MMBDTL techniques. The complementary nature of the radiative and nonradiative emission is understood from the fluorescence study. Thus, the study reveals the possibility of thermal diffusivity measurement as an effective tool for the quality monitoring of engine oil.

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Mohapatra, Sangita, Dilip Kumar Mishra et Saroj Kumar Singh. « Microscopic and spectroscopic analyses of TiC powder synthesized by thermal plasma technique ». Powder Technology 237 (mars 2013) : 41–45. http://dx.doi.org/10.1016/j.powtec.2013.01.018.

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Dev, R. K., A. Bhattarai, N. K. Chaudhary et P. Mishra. « Synthesis, Spectroscopic Characterization and Antibacterial Assessment of Zirconium(II) and Palladium(II) Complexes of Tetracycline-Salicylaldehyde Mixed Ligand ». Asian Journal of Chemistry 32, n^o 6 (2020) : 1473–81. http://dx.doi.org/10.14233/ajchem.2020.22623.

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Zirconium(II) and palladium(II) mixed ligand metal complexes were synthesized by using an equimolar mixture of tetracycline (Tc) as primary ligand and salicylaldehyde as secondary ligand. The metal complexes were characterized by physico-chemical and spectroscopic techniques like CHN analysis, surface tension, pH, conductivity and melting point measurements. The spectroscopic characterization technique includes IR, (1H & 13C) NMR, UV/visible and Mass spectrometry methods. The SEM technique determines the surface morphology of the complexes. The thermal and kinetic stability of the complexes was obtained from TGA/DTA curves from which the parameters like E*, ΔH*, ΔS* and ΔG* have been calculated by using the Coats-Redfern equation. Molecular modeling gives a geometry of the complex which was obtained from Chem 3D Pro. 12.0 software program. The metal complexes of Zr-TcSal and Pd-TcSal have coordinated with tetrahedral and square planar geometry, respectively. The antibacterial susceptibility study of the synthesized metal complexes was done by Kirby-Bauer paper disc diffusion techniques on S. aureus, E. coli and P. aeruginosa clinical pathogens

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ZHAO, JINZHE, ZHIYU QIAN, JIA LIU, YA XU et JIALI WU. « REAL-TIME ASSESSMENT OF MICROWAVE ABLATION EFFICACY BY NIR SPECTROSCOPIC TECHNIQUE ». Journal of Innovative Optical Health Sciences 07, n^o 01 (janvier 2014) : 1350053. http://dx.doi.org/10.1142/s1793545813500533.

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Microwave ablation (MWA) status monitoring in real time plays a key role in assessment of therapeutic effectiveness. As a novel real-time assessment method, near infrared spectroscopy (NIRs) was used to evaluate the ablation efficacy. MWA experiments were carried out on in vitro porcine livers. An optical measurement system for biological tissue is developed by our lab to monitor reduced scattering coefficient [Formula: see text] at 690 nm of the coagulation zones. It is noted that [Formula: see text] of liver tissue, which increases as the liver tissue being ablated, is clearly related with the coagulation status. [Formula: see text] of normal tissue and coagulated tissue is 3–5 and 17–19 cm-1, respectively. Continuous changes of [Formula: see text] demonstrate that optical parameter can be used as an efficacy evaluation factor because it essentially indicates the degree of thermal damage. Compared with temperature, optical parameter is more sensitive and accurate, which is promising for real-time therapeutic efficacy assessment in MWA.

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Lavra, T. C. C., L. A. Silva, K. S. B. Cavalcante, K. L. L. Marinho, B. A. M. Figueira et J. M. Rivas Mercury. « Microwave radiation influence on the thermal and spectroscopic properties of Na-birnessite-type material ». Cerâmica 65, n^o 376 (décembre 2019) : 547–53. http://dx.doi.org/10.1590/0366-69132019653762653.

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Abstract The aim of this work was to study the effect of the microwave radiation on the thermal and spectroscopic features, as well as about arrangement (order-disorder) and morphological properties, of the layered manganese oxide with birnessite-type structure. The route employed to obtain Na-birnessite matrix was redox precipitation. The products were characterized by X-ray diffraction, thermal analysis (TG-DTG-DSC), infrared (FTIR) and Raman spectroscopy, scanning electron microscopy (SEM) and nitrogen adsorption-desorption technique. The results showed that microwave radiation influenced in a short time (5 min) the octahedral ordering of birnessite, as well as in increasing the crystallite size. Thermal analysis showed that the thermal behavior of the lamellar matrix was different from that of birnessite under microwave radiation. After microwave-assisted hydrothermal treatment, FTIR and Raman spectroscopy investigations were used to differentiate ordered and disordered birnessites. Otherwise, there were no changes in SEM morphology of the lamellar-type phases, but the particle size changed.

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Hernández Simón, Zaira Jocelyn, Jose Alberto Luna López, Alvaro David Hernández de la Luz, Sergio Alfonso Pérez García, Alfredo Benítez Lara, Godofredo García Salgado, Jesus Carrillo López, Gabriel Omar Mendoza Conde et Hayde Patricia Martínez Hernández. « Spectroscopic Properties of Si-nc in SiOx Films Using HFCVD ». Nanomaterials 10, n^o 7 (20 juillet 2020) : 1415. http://dx.doi.org/10.3390/nano10071415.

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In the present work, non-stoichiometric silicon oxide films (SiOx) deposited using a hot filament chemical vapor deposition technique at short time and simple parameters of depositions are reported. This is motivated by the numerous potential applications of SiOx films in areas such as optoelectronics. SiOx films were characterized with different spectroscopic techniques. The deposited films have interesting characteristics such as the presence of silicon nanoclusters without applying thermal annealing, in addition to a strong photoluminescence after applying thermal annealing in the vicinity of 1.5 eV, which may be attributed to the presence of small, oxidized silicon grains (less than 2 nm) or silicon nanocrystals (Si-nc). An interesting correlation was found between oxygen content, the presence of hydrogen, and the formation of defects in the material, with parameters such as the band gap and the Urbach energies. This correlation is interesting in the development of band gap engineering for this material for applications in photonic devices.

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Bhardwaj, Bishwajeet, Takeshi Sugiyama, Naoko Namba, Takayuki Umakoshi, Takafumi Uemura, Tsuyoshi Sekitani et Prabhat Verma. « Raman Spectroscopic Studies of Dinaphthothienothiophene (DNTT) ». Materials 12, n^o 4 (18 février 2019) : 615. http://dx.doi.org/10.3390/ma12040615.

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The application of dinaphthothienothiophene (DNTT) molecules, a novel organic semiconductor material, has recently increased due to its high charge carrier mobility and thermal stability. Since the structural properties of DNTT molecules, such as the molecular density distribution and molecular orientations, significantly affect their charge carrier mobility in organic field-effect transistors devices, investigating these properties would be important. Here, we report Raman spectroscopic studies on DNTT in a transistor device, which was further analyzed by the density functional theory. We also show a perspective of this technique for orientation analysis of DNTT molecules within a transistor device.

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Perumal, R., S. Thanikaikarasan, M. Saravannan, R. Kanimozhi et S. Sudharthini. « Influence of Halogens on the Growth Aspects of Allylthiourea Cadmium Complex Nonlinear Optical Single Crystals ». Journal of New Materials for Electrochemical Systems 25, n^o 2 (10 juin 2022) : 110–15. http://dx.doi.org/10.14447/jnmes.v25i2.a04.

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Allylthiourea complex crystals is an organometallic complex, a new nonlinear optical materials with high second harmonic generation effect. Tri-allylthiourea cadmium chloride and Tri-allylthiourea cadmium bromide are the promising nonlinear optical crystals belonging to this family. Both the crystals have been grown from an aqueous solution by slow cooling technique. The solubility and growth optimization of the grown crystals in terms of pH were analyzed and the influence of the different halogen atoms on the properties of as grown single crystals was studied by conducting various characterization techniques. Powder X-ray diffraction studies revealed that both the crystals are trigonal crystal structure with R3C space group. The spectroscopic properties were investigated by recording the Fourier Transform Infra Red and UV-Visible-NIR spectroscopy. Spectrocopic study confirmed the coordination of metal and red shift of the grown crystal. Nonlinear behavior of the as grown crystals was identified by Kurtz powder technique. Thermal and electrical properties of the as grown crystals were also analyzed by thermogravimetric and dielectric studies. Influence of the halogens on the growth as well as the properties were studied.

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Chavez-Angel, Emigdio, Blanca Puertas, Martin Kreuzer, Robert Soliva Fortuny, Ryan C. Ng, Alejandro Castro-Alvarez et Clivia M. Sotomayor Torres. « Spectroscopic and Thermal Characterization of Extra Virgin Olive Oil Adulterated with Edible Oils ». Foods 11, n^o 9 (29 avril 2022) : 1304. http://dx.doi.org/10.3390/foods11091304.

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The substitution of extra virgin olive oil with other edible oils is the primary method for fraud in the olive-oil industry. Developing inexpensive analytical methods for confirming the quality and authenticity of olive oils is a major strategy towards combatting food fraud. Current methods used to detect such adulterations require complicated time- and resource-intensive preparation steps. In this work, a comparative study incorporating Raman and infrared spectroscopies, photoluminescence, and thermal-conductivity measurements of different sets of adulterated olive oils is presented. The potential of each characterization technique to detect traces of adulteration in extra virgin olive oils is evaluated. Concentrations of adulterant on the order of 5% can be detected in the Raman, infrared, and photoluminescence spectra. Small changes in thermal conductivity were also found for varying amounts of adulterants. While each of these techniques may individually be unable to identify impurity adulterants, the combination of these techniques together provides a holistic approach to validate the purity and authenticity of olive oils.

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Kafarska, Karolina, Michał Gacki et Wojciech M. Wolf. « Synthesis, Spectroscopic, and Thermal Investigations of Metal Complexes with Mefenamic Acid ». Journal of Chemistry 2017 (2017) : 1–7. http://dx.doi.org/10.1155/2017/6172626.

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The novel metal complexes with empirical formulae M(mef)2·nH2O (where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); mef is the mefenamic ligand) were synthesized and characterized by elemental analysis, molar conductance, FTIR-spectroscopy, and thermal decomposition techniques. All IR spectra revealed absorption bands related to the asymmetric (νas) and symmetric (νs) vibrations of carboxylate group. The Nakamoto criteria clearly indicate that this group is bonded in a bidentate chelate mode. The thermal behavior of complexes was studied by TGA methods under non-isothermal condition in air. Upon heating, all compounds decompose progressively to metal oxides, which are the final products of pyrolysis. Cu(II), Zn(II), and Cd(II) complexes were also characterized by the coupled TG-FTIR technique, which finally proved the path and gaseous products of thermal decomposition. Additionally, the coupled TG-MS system was used to determine the principal volatile products of thermolysis and fragmentation processes of Mn(mef)2·3H2O and Co(mef)2·2H2O.

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Grolier, Jean-Pierre E. « Advanced experimental techniques in polymer thermodynamics ». Pure and Applied Chemistry 77, n^o 8 (1 janvier 2005) : 1297–315. http://dx.doi.org/10.1351/pac200577081297.

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Scanning transitiometry is at the center of several new developments to generate original unprecedented data over extended ranges of temperatures and pressures. Simultaneous in situ spectroscopic readings noticeably extend the performance of scanning transitiometry. The modulation of temperature superimposed to temperature scanning for thermal analysis is a major step forward to unambiguously identify glass transitions from other overlapping phenomena. The combination of a weighing technique (vibrating-wire technique) with a pressure decay technique (pVT technique) allows us to estimate simultaneously, in situ on the same polymer sample, the gas solubility and the concomitant polymer swelling.

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Pryshchepa, Oleksandra, Gulyaim N. Sagandykova, Paweł Pomastowski, Viorica Railean-Plugaru, Anna Król, Agnieszka Rogowska, Agnieszka Rodzik, Myroslav Sprynskyy et Bogusław Buszewski. « A New Approach for Spontaneous Silver Ions Immobilization onto Casein ». International Journal of Molecular Sciences 20, n^o 16 (8 août 2019) : 3864. http://dx.doi.org/10.3390/ijms20163864.

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The work presents the kinetic and isotherm studies of silver binding on casein, which was carried out using batch sorption technique. Moreover, the influence of light irradiation on the process was shown. In order to investigate the mechanism of metal ions sorption by casein the zero, pseudo-first order kinetics and Weber-Morris intra-particle diffusion as well as Langmuir and Freundlich isotherm models were used. Furthermore, to specify more precisely, the possible binding mechanism, the spectroscopic (FT-IR—Fourier Transform Infrared Spectroscopy, Raman), spectrometric (MALDI-TOF MS—Matrix-Assisted Laser Desorption/Ionization Time Of Flight Mass Spectrometry), microscopic (SEM—Scanning Electron Microscope, TEM/EDX—Transmission Electron Microscopy/Energy Dispersive X-ray detector) and thermal (TGA—Thermogravimetric Analysis, DTG—Derivative Thermogravimetry) analysis were performed. Kinetic study indicates that silver binding onto casein is a heterogeneous process with two main stages: initial rapid stage related to surface adsorption onto casein with immediate creation of silver nanoparticles and slower second stage of intraglobular diffusion with silver binding in chelated form (metalloproteins) or ion-exchange form. Spectroscopic techniques confirmed the binding process and MALDI-TOF MS analysis show the dominant contribution of the α-casein in the process. Moreover, the treatment of silver-casein complex by artificial physiological fluids was performed.

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Bale, Shashidhar, et Syed Rahman. « Spectroscopic and Physical Properties of --ZnO- Glasses ». ISRN Spectroscopy 2012 (29 février 2012) : 1–7. http://dx.doi.org/10.5402/2012/634571.

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Bismuth glasses containing ZnO and Li2O were prepared by conventional melt-quench technique. ZnO is gradually substituted by Li2O, and its effect on various physical, thermal, and electrical conduction properties was studied and analyzed. Raman studies revealed that these glasses are mainly made up of [BiO3] and [BiO6] units. The density decreases and molar volume increases with the incorporation of Li2O into these glasses. MDSC studies have been performed on these glasses to determine the glass transition temperature and other related thermal parameters such as change in the glass transition temperature () and specific heat capacity difference (). These studies revealed that the glasses possess high values, and decreases with Li2O content. The trend of these properties is attributed to the changes in the glass network structure. Dc electrical conductivity revealed that the conductivity increases and activation energy decreases with Li2O content.

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Anandhi, S., D. Keerthika, M. Leo Edward et V. Jaisankar. « Synthesis and Characterization of Niobium Oxide Nanoparticles, Polyindole and Nb2O5/Polyindole Nanocomposite ». Asian Journal of Chemistry 32, n^o 3 (31 janvier 2020) : 653–58. http://dx.doi.org/10.14233/ajchem.2020.22397.

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In present work, polyindole-Nb2O5 nanocomposite was synthesized and characterized by various analytical methods. Niobium oxide nanoparticles were prepared by sol gel method. Polyindole and Nb2O5 nanocomposites was prepared by chemical polymerization method and the morphology of Nb2O5 nanoparticles, polyindole and the nanocomposite was studied by SEM. The chemical structure of Nb2O5 nanoparticle, polyindole and the nanocomposite was characterized by UV-visible, FTIR and NMR spectroscopic techniques. Elemental composition and chemical character was analyzed by the use of EDAX technique. The X-ray powder diffraction technique was used to determine the degree of crystallinity and crystallite sizes. Thermal analysis such as TGA and DSC showed that the conducting polymers in the nanocomposites were stable even at high temperatures.

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Dadarlat, D., C. Tripon, Iain R. White et Dorota Korte. « Photopyroelectric spectroscopy and calorimetry ». Journal of Applied Physics 132, n^o 19 (21 novembre 2022) : 191101. http://dx.doi.org/10.1063/5.0085594.

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In this Tutorial, we present an overview of the development of the photopyroelectric (PPE) technique from its beginning in 1984 to the present day. The Tutorial is organized into five sections, which explore both theoretical and experimental aspects of PPE detection as well as some important spectroscopic and calorimetric applications. In the “Introduction” section, we present the fundamental basics of photothermal phenomena and the state-of-the-art of photopyroelectric technique. In the “Theoretical aspects” section, we describe some specific cases of experimental interest, with examples in both back and front detection configurations. Several mathematical expressions for the PPE signal in specific detection modes (combined back–front configurations and PPE–thermography methods) are also deduced. The “Instrumentation and experiment” section contains two subsections. The first describes several examples of setups used for both room temperature and temperature-controlled experiments. The second subsection is dedicated to the configuration of detection cells and to the various sensor/sample assemblies that are currently used in spectroscopic and calorimetric experiments for both liquid and solid samples. The “Applications” section is in fact a collection of experimental results dedicated to the thermal characterization of a wide range of solid and liquid samples. At the end of this section, we present some examples that have been selected to convey that the PPE technique is not only useful in the investigation of optical and thermal properties of a variety of condensed matter samples, but also to study physical and chemical processes such as molecular associations, food adulteration, or phase transitions. In “Concluding remarks,” we summarize the advantages of this technique in spectroscopic and calorimetric applications.

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Stoica, Rusandica, Florin Oancea, Iulian Minca, Sanda Maria Doncea, Rodica Ganea, Luiza Capra, Raluca Senin et al. « Spectroscopic, Textural and Thermal Characterization Methods of Biostimulants Based on Sodium Humate ». Revista de Chimie 69, n^o 12 (15 janvier 2019) : 3477–82. http://dx.doi.org/10.37358/rc.18.12.6773.

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Plant biostimulants, an emerging class of agricultural inputs, are complex products. The reproducibility of their specific action on plant metabolism and plant physiology, which lead to an enhanced nutrient use efficiency, stress tolerance and edible yield quality, is still a challenge. Development of quality insurance systems for plant biostimulants need complex investigation based on adapted analytical, physico-chemical and chemical methods. The objective of this work was to characterize commercial humate biostimulants through different analytical techniques (Fourier transform infrared spectroscopy - FTIR, thermogravimetric analysis- TGA) and to evaluate their textural and chemical (pH, C, N, humic acids, inorganic components) parameters. The first derivative curve from TG analysis showed decomposition of different compounds, classified according to the results obtained by FTIR. The humic substances determined by TGA method was comparable with the results obtained by gravimetric reference method. The inductively coupled plasma-optical emission spectrometry (ICP-OES) technique was applied to determine the inorganic elements either from the production process of humate or from raw materials, as well as for the control of humate in terms of requirements for safety and quality. Their complementary properties obtaining through different analytical techniques provide essential information on the chemical characteristics of the humate plant biostimulant formulations.

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Martini, Andrea, et Elisa Borfecchia. « Spectral Decomposition of X-ray Absorption Spectroscopy Datasets : Methods and Applications ». Crystals 10, n^o 8 (1 août 2020) : 664. http://dx.doi.org/10.3390/cryst10080664.

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X-ray absorption spectroscopy (XAS) today represents a widespread and powerful technique, able to monitor complex systems under in situ and operando conditions, while external variables, such us sampling time, sample temperature or even beam position over the analysed sample, are varied. X-ray absorption spectroscopy is an element-selective but bulk-averaging technique. Each measured XAS spectrum can be seen as an average signal arising from all the absorber-containing species/configurations present in the sample under study. The acquired XAS data are thus represented by a spectroscopic mixture composed of superimposed spectral profiles associated to well-defined components, characterised by concentration values evolving in the course of the experiment. The decomposition of an experimental XAS dataset in a set of pure spectral and concentration values is a typical example of an inverse problem and it goes, usually, under the name of multivariate curve resolution (MCR). In the present work, we present an overview on the major techniques developed to realize the MCR decomposition together with a selection of related results, with an emphasis on applications in catalysis. Therein, we will highlight the great potential of these methods which are imposing as an essential tool for quantitative analysis of large XAS datasets as well as the directions for further development in synergy with the continuous instrumental progresses at synchrotron sources.

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Lima, S. M., et T. Catunda. « Spectroscopic study of ds/dT in commercial filter by using the thermal lens technique ». Journal de Physique IV (Proceedings) 125 (juin 2005) : 221–23. http://dx.doi.org/10.1051/jp4:2005125052.

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de Portu, Gofferedo, Lorenzo Micele, Manuel Alberto Roldán Gutiérrez, Leonardo Puppulin, Maria Chiara Munisso, Cesare Melandri et Giuseppe Pezzotti. « New Method to Measure Thermal Shock Resistance in Ceramics Using a Piezo-Spectroscopic Technique ». Journal of the American Ceramic Society 91, n^o 4 (avril 2008) : 1316–18. http://dx.doi.org/10.1111/j.1551-2916.2007.02245.x.

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Mathew, Manjusha Elizabeth, Ishak Ahmad, Sabu Thomas, Muhammad Kassim et Rusli Daik. « A Preliminary Study on the Synthesis of poly(vinylbenzyl chloride) with Different Solvents ». Sains Malaysiana 50, n^o 6 (30 juin 2021) : 1767–73. http://dx.doi.org/10.17576/jsm-2021-5006-22.

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Polyvinyl benzyl chloride (PVBC) was synthesized by free radical polymerization of 4-vinylbenzyl chloride using benzoyl peroxide initiator at 60 °C. PVBC was synthesised in different solvents such as toluene, xylene, 1,4-dioxane, and tetrahydrofuran. The polymers were structurally characterized by 1H NMR and FTIR spectroscopic techniques. The thermal property of the polymer was investigated by thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTA).The number average molecular weight, weight average molecular weight and polydispersity index of PVBC synthesised in different solvents were determined and compared by gel permeation chromatography technique.

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Anjum, Zakia, N. U. rehman, Maria Younus et Sajjad Sarwar. « Spectroscopic investigation of non-thermal plasma generated in atmospheric pressure ‘Plasma Pencil’ ». International Journal of Modern Physics B 34, n^o 11 (30 avril 2020) : 2050112. http://dx.doi.org/10.1142/s021797922050112x.

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Plasma generated at atmospheric pressure has widespread applications in the field of plasma medicine. In this paper, spectroscopic investigations of homemade capacitively coupled, atmospheric pressure RF plasma pencil is reported. Optical emission spectroscopy (OES) technique is employed to characterize the plasma. Variation in rotational/gas temperature [Formula: see text], [Formula: see text] atomic density, dissociation fraction [Formula: see text] and normalized intensities of [Formula: see text], [Formula: see text] and [Formula: see text] radiation is monitored as a function of discharge parameters like RF power and different gases concentration. [Formula: see text] of [Formula: see text] mixture is estimated from [Formula: see text] band head of R branch of first negative system of nitrogen [Formula: see text], [Formula: see text], [Formula: see text] using Boltzmann plot technique. Similarly, [Formula: see text] band head of second positive system (SPS) of nitrogen [Formula: see text], [Formula: see text], [Formula: see text] is also used to estimate [Formula: see text] by fitting synthetic spectra over the experimentally recorded spectrum. It is noted that [Formula: see text] increases with increase in RF power, but it decreases with increase in [Formula: see text] concentration in the mixture. [Formula: see text] atomic density and dissociation fraction [Formula: see text], estimated from [Formula: see text] line at 750 nm and [Formula: see text] line at 844 nm using actinometry technique, show increasing trend with RF power and [Formula: see text] concentration in the mixture up to 0.7% [Formula: see text] in the mixture. The normalized [Formula: see text] radiation intensities; [Formula: see text], [Formula: see text] and [Formula: see text] show the increasing trend with increase in RF power up to 0.3% [Formula: see text] concentration in the mixture.

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Muhammad Ikram, Muhammad Ikram, Sadia Rehman Sadia Rehman, Muhammad Ayaz Muhammad Ayaz, Syed Muhammad Salman Syed Muhammad Salman, Farzia Farzia, Muhammad Imran Muhammad Imran, Mutasem Omar Sinnokrot Mutasem Omar Sinnokrot, Farman Ullah Farman Ullah et Bushra Khan Bushra Khan. « Synthesis, Spectral, Thermal and DPPH Scavenging Studies of the Hydrazone Derived Transition Metal Complexes ». Journal of the chemical society of pakistan 42, n^o 6 (2020) : 888. http://dx.doi.org/10.52568/000691.

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Schiff base ligand 2,2-{benzene-1,4-diylbis[(E)methylylidene(1E,2E)hydrazine-2,1-diylidene(E)methylidene]}diphenol (H2-BHMD) was synthesized by reacting together the ortho vaniline and 1,4-bis(hydrazonomethyl)benzene. It was characterized by analytical and spectroscopic techniques including 1H-NMR, elemental analysis, FT-IR, and UV-Visible studies. Different transition metal ions like Co (II), Ni (II), Cu (II) and Zn (II) were reacted with well characterized ligand to obtain the metal derivatives. AAS, elemental analysis, FT-IR, molar conductance and UV-Visible methods were used to study the metal complexes. The analytical and spectroscopic technique suggested the formation of coordination polymers. The FT-IR results conﬁrmed the bidentate binding of the ligand involving phenolic oxygen and azomethine nitrogen. The UV-visible studies suggested the formation of distorted square planar geometries for all the metal complexes. Hydrazone Schiff bases are known for their antioxidant activity, therefore the synthesized hydrazone and the corresponding metal complexes were also studied for their antioxidant capabilities utilizing DPPH free radicals. Among all complexes, the Co-BHMD demonstrated noteworthy percent hindrance to the free radicals, yet much lower than the standard medication utilized. The metal subsidiaries were likewise studied for their thermal degradation. The respective TG bands were utilized for dynamic and thermodynamic parameters estimation utilizing Horowitz-Metzger strategy.

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Muhammad Ikram, Muhammad Ikram, Sadia Rehman Sadia Rehman, Muhammad Ayaz Muhammad Ayaz, Syed Muhammad Salman Syed Muhammad Salman, Farzia Farzia, Muhammad Imran Muhammad Imran, Mutasem Omar Sinnokrot Mutasem Omar Sinnokrot, Farman Ullah Farman Ullah et Bushra Khan Bushra Khan. « Synthesis, Spectral, Thermal and DPPH Scavenging Studies of the Hydrazone Derived Transition Metal Complexes ». Journal of the chemical society of pakistan 42, n^o 6 (2020) : 888. http://dx.doi.org/10.52568/000691/jcsp/42.06.2020.

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Schiff base ligand 2,2-{benzene-1,4-diylbis[(E)methylylidene(1E,2E)hydrazine-2,1-diylidene(E)methylidene]}diphenol (H2-BHMD) was synthesized by reacting together the ortho vaniline and 1,4-bis(hydrazonomethyl)benzene. It was characterized by analytical and spectroscopic techniques including 1H-NMR, elemental analysis, FT-IR, and UV-Visible studies. Different transition metal ions like Co (II), Ni (II), Cu (II) and Zn (II) were reacted with well characterized ligand to obtain the metal derivatives. AAS, elemental analysis, FT-IR, molar conductance and UV-Visible methods were used to study the metal complexes. The analytical and spectroscopic technique suggested the formation of coordination polymers. The FT-IR results conﬁrmed the bidentate binding of the ligand involving phenolic oxygen and azomethine nitrogen. The UV-visible studies suggested the formation of distorted square planar geometries for all the metal complexes. Hydrazone Schiff bases are known for their antioxidant activity, therefore the synthesized hydrazone and the corresponding metal complexes were also studied for their antioxidant capabilities utilizing DPPH free radicals. Among all complexes, the Co-BHMD demonstrated noteworthy percent hindrance to the free radicals, yet much lower than the standard medication utilized. The metal subsidiaries were likewise studied for their thermal degradation. The respective TG bands were utilized for dynamic and thermodynamic parameters estimation utilizing Horowitz-Metzger strategy.

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Darwish, Saqer M., Jafar Ghithan, Musa M. Abuteir, Mariam Faroun et Mahmoud M. Abu-hadid. « Spectroscopic Investigations of Pentobarbital Interaction with Transthyretin ». Journal of Spectroscopy 2013 (2013) : 1–10. http://dx.doi.org/10.1155/2013/927962.

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Transthyretin (TTR) aggregation has been characterized to be responsible for several amyloid diseases. Fourier transform infrared (FTIR) spectroscopy, fluorescence, and atomic force microscopy (AFM) are used to investigate secondary structure changes in transthyretin, induced upon thermal denaturation and interaction with pentobarbital. Spectral analysis revealed a strong static quenching of the intrinsic fluorescence of TTR by pentobarbital with a binding constant (K) estimated at2.092×103 M-1. Fourier self-deconvolution (FSD) technique is used to evaluates intensity changes in the spectra of the component bands in the amide I and amide II regions due to the changes in pentobarbital concentration in the protein complex. The increases of the relative intensities of the peaks at 1614 cm−1and 1507 cm−1are due to the increase of pentobarbital concentrations which is linked to the formation of oligomers in the protein.

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Suganthi, R., S. Padmaja et S. Jhancy Mary. « Magnetic, Thermal and Electrical Transport Properties of o-Substituted Polyanilines Encapsulated with Fe2O3 Nanoparticles ». Asian Journal of Chemistry 32, n^o 2 (30 décembre 2019) : 265–70. http://dx.doi.org/10.14233/ajchem.2020.22306.

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Poly(2-nitroaniline), poly(2-nitroaniline)-Fe2O3 and poly(2-methylaniline)-Fe2O3 nanocomposites synthesized by in situ chemical oxidative polymerization technique were characterized by XRD, thermal (TGA and DTA) and FTIR & UV-visible spectroscopic techniques. The thermal stability was confirmed by the integral procedural decomposition temperature (IPDT) and oxidation index (OI) calculations. The electrical conductivity and dielectric properties were also investigated. At low frequency region, the dielectric constant decreases with increase in frequency due to electrical relaxation process. At high frequencies, dielectric constant is independent of frequency. At low frequency, there was strong frequency dispersion of permittivity and above 3 Hz, a frequency independent behaviour in permittivity was observed. The materials exhibit ferromagnetic behaviour.

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Selvarajan, P., B. N. Das, H. B. Gon et K. V. Rao. « Infrared spectroscopic and thermal studies of calcium tartrate single crystals grown by silica-gel technique ». Journal of Materials Science Letters 12, n^o 15 (janvier 1993) : 1210–11. http://dx.doi.org/10.1007/bf00274502.

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Devina Merin, D., R. Anith Jose, T. S. Arulananth, Antony Allwyn Sundarraj, T. M. Inbamalar et Meseret Getnet Meharie. « Nanoclay-Incorporated Polycaprolactone Matrix via Electrospinning Techniques-Enriched Spectroscopic Responses ». Journal of Nanomaterials 2023 (13 février 2023) : 1–8. http://dx.doi.org/10.1155/2023/1194158.

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Nanotechnology is one of the most common areas for current research and development in almost all technological fields. A significant factor is the synergistic benefit of nanoscale dimensions over larger scale alteration. Polymer nanoscience is the analysis and application of nanotechnology to polymer nanoparticle matrices, with nanoparticles described as those with at least one dimension of less than 100 nm. The use of polymer nanotechnology and nanocomposites in practical applications is a rapidly developing area. For making polymeric nanofibers from polymer melts and solutions, a spinning technique is used known as electrospinning. Electrospinning is an easy way to produce ultrafine fibers, which is nanosize. For its wide range of variety of spinning polymeric fibers, it is recommended, as well as producing fibers in nanosize accurately. The aim of this project is to use electrospinning to make nanoclay integrated polycaprolactone membranes. The effects of the nanoclay on morphology, thermal, and sorption behaviors of the electrospun membrane were further studied. The scope of this project work is that the electrospun nanocomposites are best studied for biomedical applications. Because of their influence over porosity, pore size, and fiber diameter, they make excellent scaffold materials.

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Singru, Rajesh N. « Thermogravimetric and Spectroscopic Analysis of 8-Hydroxyquinoline 5-Sulphonic Acid-melamine-formaldehyde Polymer Resin-IV ». ISRN Thermodynamics 2012 (29 février 2012) : 1–8. http://dx.doi.org/10.5402/2012/323916.

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The title terpolymer (8-HQ5-SAMF-IV) synthesized by the condensation of 8-hydroxyquinoline 5-sulphonic acid (8-HQ5-SA) and melamine (M) with formaldehyde (F) in the presence of acid catalyst and using varied 3 : 1 : 5 molar proportions of the reacting monomers. The synthesized terpolymer was characterized by different physicochemical techniques. The thermogravimetric analysis of terpolymer resin prepared in the present study has been carried out by nonisothermal thermogravimetric analysis technique in which sample is subjected to condition of continuous increase in temperature at linear rate. Thermal study of the resin was carried out to determine the mode of decomposition and thermal stability. Thermal decomposition curve was studied carefully with minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used in the present investigation to calculate thermal activation energy and different kinetic parameter of the terpolymer resin. Thermal activation energy () calculated by two above mentioned methods, is in close agreement. The advantage of Freeman-Carroll method is to calculate both the order of reaction (n) and energy of activation in one single stage by keeping heating rate constant. By using data of thermogravimetric analysis, various thermogravimetric parameters like frequency factor (Z), entropy change (ΔS), free energy change (ΔF), and apparent entropy () have been determined using Freeman-Carroll method.

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SIMON, S., R. GRECU et V. SIMON. « INFRARED SPECTROSCOPIC STUDIES ON AMORPHOUS AND CRYSTALLINE LANTHANUM ALUMINOBORATES ». Modern Physics Letters B 16, n^o 08 (10 avril 2002) : 291–98. http://dx.doi.org/10.1142/s0217984902003749.

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The development of lanthanum aluminoborate crystalline phase of LaAl 2.03 B 4 O 10.5 (124) composition from the amorphous xerogels prepared by sol-gel technique has been characterized by thermal analysis and infrared spectroscopy. Thermal analysis evidenced continuous weight losses up to 800°C as a result of nitrates decomposition, glycerol combustion and dehydroxylation. The crystallization of amorphous xerogels occurs between 760 and 860°C. The IR data indicate that the local structure dramatically modifies as crystalline phases are developed from the amorphous xerogels. The major changes occur in the boron surrounding where, from the most borons which are three-coordinated in amorphous xerogels, almost only tetra-coordinated species appear in the crystalline samples. While in amorphous xerogels, aluminum occurs as hexa-, penta- and tetra-coordinated by oxygen, in the crystalline samples obtained from lanthanum aluminoborates, amorphous precursors of composition corresponding to 124-lanthanum aluminoborate phase aluminum, it is preponderantly penta- and hexa-coordinated.

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Kannan, Rajesh, G. Narayanasamy, S. Subramanian et P. Selvarajan. « Spectroscopic, thermal, second order and third order NLO studies of N, N’ -dimethyl urea crystal ». Journal of Applied and Advanced Research 1, n^o 1 (23 janvier 2018) : 1. http://dx.doi.org/10.21839/jaar.2018.v1i1.124.

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Nonlinear optical (NLO) crystals are classified into organic, inorganic and semi organic crystals and these crystals are used in the fields of optical communication, optical computing, frequency doubling, optical data processing and opto electronics. In this work an organic NLO crystal namely DMU crystal was prepared. Slow evaporation technique was adopted to grow the single crystals of DMU after the growth period of 35 days. The harvested crystals have been subjected to various characterization techniques like XRD, FTIR, FT-Raman, TG/DTA, SHG, EDAX, impedance, optical and Z-scan studies. From the studies, is observed that DMU crystal has orthorhombic structure and it has the melting point at 105 oC and has the decomposition point at 275 oC. The relative SHG efficiency of DMU crystal was found to be more than one and third order NLO parameters were evaluated. The optical band gap of DMU crystal was found to be 5.008 eV.The results from various studies were analyzed.

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Kannan, Rajesh, G. Narayanasamy, S. Subramanian et P. Selvarajan. « Spectroscopic, thermal, second order and third order NLO studies of N, N’ -dimethyl urea crystal ». Journal of Applied and Advanced Research 3, n^o 1 (23 janvier 2018) : 1. http://dx.doi.org/10.21839/jaar.2018.v3i1.124.

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Nonlinear optical (NLO) crystals are classified into organic, inorganic and semi organic crystals and these crystals are used in the fields of optical communication, optical computing, frequency doubling, optical data processing and opto electronics. In this work an organic NLO crystal namely DMU crystal was prepared. Slow evaporation technique was adopted to grow the single crystals of DMU after the growth period of 35 days. The harvested crystals have been subjected to various characterization techniques like XRD, FTIR, FT-Raman, TG/DTA, SHG, EDAX, impedance, optical and Z-scan studies. From the studies, is observed that DMU crystal has orthorhombic structure and it has the melting point at 105 oC and has the decomposition point at 275 oC. The relative SHG efficiency of DMU crystal was found to be more than one and third order NLO parameters were evaluated. The optical band gap of DMU crystal was found to be 5.008 eV.The results from various studies were analyzed.

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Saharia, Balen, Gouranga Das et Bipul Nath. « COMPATIBILITY SCREENING OF VIDAGLIPTIN WITH IONIC AND NON-IONIC POLYMERIC EXCIPIENTS FOR THE DESIGN OF EXTENDED RELEASE DELIVERY SYSTEM ». International Journal of Advanced Research 9, n^o 04 (30 avril 2021) : 187–93. http://dx.doi.org/10.21474/ijar01/12671.

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Studies of drug-polymer compatibility play an important role in the preformulation stage for the development of pharmaceutical dosage forms. The potential physical and chemical interactions between drugs and polymer can affect the chemical nature, stability and bioavailability of the dosage form and as a result in the therapeutic response in the clinical phase. The present study reveals the thermal and spectroscopic study of physical mixtures of Vildagliptin (VDG) and HPMC in combination with cationic polymers chitosan, anionic polymers NaCMC and nonionic polymers PEO for extended release (ER). In the first phase of the study, differential scanning calorimeter (DSC) was used as tool to detect any interaction. In the next phase, a Fourier Transform Infrared Spectroscopy (FT-IR) technique was used to confirm and to investigate the type of the possible interactions between the components. In both cases, the spectroscopic data revealed that the analysed polymeric excipients did not show any affect on the VDG. Results of the present study indicated the suitability of the HPMC K4M hydrophilic matrix polymers in combination with cationic polymers, anionic polymers and non-ionic polymers in the preparation of extended release formulation of VDG.

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Bielinski, Ashley R., et Alex B. F. Martinson. « (Invited) Investigating Surface Reaction Thermodynamics : In Situ Calorimetry for Atomic Layer Deposition ». ECS Meeting Abstracts MA2022-02, n^o 31 (9 octobre 2022) : 1124. http://dx.doi.org/10.1149/ma2022-02311124mtgabs.

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Atomic layer deposition (ALD) is comprised of sequential self-limiting surface reactions that are inherently sensitive to the surface chemistry of the substrate and the reactivity of the chosen precursors. In order to better understand ALD processes and direct their future development we must investigate the fundamental mechanisms of ALD reactions. This is commonly done using a combination of computational modeling and experimental investigations using techniques like spectroscopic ellipsometry and IR spectroscopy. We present pyroelectric calorimetry for ALD as an in situ technique to measure the time resolved heat generation from ALD reactions. This provides a new dimension of thermodynamic and kinetic reaction data. As an experimental technique, pyroelectric calorimetry measures ALD reactions on realistic surfaces as opposed to idealized models. We have designed and constructed custom calorimeters that are compatible with typical ALD process parameters. These calorimeters have been calibrated with a thermal resolution down to 0.1 μJ/cm2 and a temporal resolution of 50ns. To put this in perspective for an ALD reaction, this corresponds to about 0.1% of the heat evolved in the trimethylaluminum (TMA) and water ALD process and about 104 faster than our measurement of the TMA half reaction. The temporal resolution of our calorimeters is orders of magnitude faster than most complementary in situ analysis techniques including ellipsometry, IR spectroscopy, quartz crystal microgravimetry, and mass spectrometry. This time resolution provides information on precursor flow dynamics and reaction kinetics. Pyroelectric calorimetry was used to investigate the TMA and water half reactions for ALD Al2O3 along with in situ spectroscopic ellipsometry thickness measurements and Rutherford backscattering spectrometry (RBS) composition analysis. This enabled comparisons of the change in thickness with the amount of heat generated as each half reaction saturates. Atomic growth rates calculated form RBS were used to calculate the heat generated on a per-atom basis. These results were then compared with proposed reaction mechanisms and energy changes from density functional theory (DFT) computational modeling. Measurements of reaction and adsorption heats can also be used to compare and evaluate different precursors and inhibitor molecules for ALD growth inhibition in area-selective ALD. We investigated how the thermodynamics of adsorption can guide our choice of precursor-inhibitor pairs when using small molecule inhibitors that rely on competitive adsorption and chemical passivation to prevent ALD growth. Pyroelectric calorimetry offers new insight into what drives and limits ALD reactions and provides many opportunities for future investigations.

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Curry, Erin B., Kaitlin C. Lyszak, Donal Sheets, Lauren M. Gorman, Rainer J. Hebert et Jason N. Hancock. « Broadband infrared confocal imaging for applications in additive manufacturing ». Review of Scientific Instruments 93, n^o 12 (1 décembre 2022) : 123702. http://dx.doi.org/10.1063/5.0124817.

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We address new measurement challenges relating to 3D printing in metal powder using the powder bed fusion technique. Using a combination of confocal microscopy principles and fast, sensitive mid-infrared collection techniques, we present a compact and versatile method of measuring and analyzing broadband thermal emissions from the vicinity of the molten metal pool during the additive manufacturing process. We demonstrate the benefits of this instrumentation and potential for scientific research as well as in situ monitoring. Our compact microscope collection optics can be implemented in various powder bed fusion machines under vacuum or inert atmospheric environments to enable extensions such as multi-color pyrometry or spectroscopic studies of additive manufacturing processes.

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Jain, Shilpa, Rashmi Sharma et Arun K. Sharma. « Solid State Kinetics, Spectroscopic, Thermal Degradation and Fungicidal Studies of Biodegradable Copper Surfactants Derived from Lauric Acid ». Anti-Infective Agents 18, n^o 1 (4 février 2020) : 59–71. http://dx.doi.org/10.2174/2211352517666190514074750.

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Introduction: The synthesis of copper soap (laurate), and its complex with 2-amino 6- methylbenzothiazole and their elemental and spectral analysis have been done for comparative studies using IR, NMR, Mass and ESR spectra. Methods: The fungicidal activities, with reference to Alternaria alternata and Aspergillus niger at different concentrations by P.D.A. technique were also studied. Results and Conclusion: The present research work comprises detailed thermal analysis using TGA technique to determine their kinetic and thermodynamic parameters by applying various equations like Freeman Carroll, Coats-Redfern equation, Horowitz-Metzger equation, Broido equation, Piloyan–Novikova equation.

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Raj, Vimal, Mohanachandran Nair Sindhu Swapna et Sankaranarayana Iyer Sankararaman. « Criticality of depth of intensity modulation and simulation of refractive index profile in thermal lens technique ». European Physical Journal Applied Physics 90, n^o 1 (avril 2020) : 11001. http://dx.doi.org/10.1051/epjap/2020200024.

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The present paper intends to unveil the criticality of the depth of intensity modulation (D) in getting correct results in optical experiments employing electromechanical choppers. The study elucidates experimentally using a single beam thermal lens setup with an optical chopper with variable D, designed and constructed cost-effectively, and also by simulating the refractive index profile generated within the medium. The thermal diffusivity of water with a trace amount of chlorophyll is determined by varying D for a given period. It is observed that for a D above 10%, photodissociation and Soret effect significantly affect the thermal lens signal and thereby giving erroneous value to the thermal diffusivity. The UV-visible spectroscopic analysis reveals reduced absorption for the leaf pigments − chlorophyll a, chlorophyll b, and lutein as a result of photodissociation. Thus the study demonstrates the criticality of D for obtaining error-free measurements.

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Islam, M. Nurul, S. M. Mahruf Hossain, A. Khatton, M. M. Rahman, J. Sarker, H. A. Sikder et A. M. Sarwaruddin Chowdhury. « Microcrystalline Cellulose from Jute Fiber : A Bright Prospect for Pharmaceutical Industry ». Scholars International Journal of Chemistry and Material Sciences 5, n^o 6 (16 août 2022) : 100–104. http://dx.doi.org/10.36348/sijcms.2022.v05i06.003.

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Synthesis of microcrystalline cellulose (MCC) from jute sticks has been studied and reported in this work. The successful removal of lignin and hemi-cellulose has been confirmed through Fourier Transform Infrared (FTIR) spectroscopic technique. X-ray Diffraction (XRD) technique has been used to measure the crystal size and crystallinity index. The FTIR analysis revealed that the acid hydrolysis had an effect on the crystalline of the fibre; however it did not influence the chemical components of the fibres. Pharmaceutical standard tests were done. Higher concentration of sodium chlorite produces minimum particle size and the effective thermal degradation occurs at 340 °C.

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Articles de revues sur le sujet « Thermic and spectroscopic technique »

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