Real-time IR Research Articles

Infrared in-line monitoring of flaws in steel welded joints: a preliminary approach with SMAW and GMAW processes

The non-destructive full-field non-contact thermographic technique is applied for non-destructive flaw detection of the welded joints, in real-time and offline configuration. In this paper, a thermographic procedure for real-time flaw detection in manual arc welding process is presented. Surface temperature acquisitions by means of an IR camera were performed during arc welding process of 8 specimen both for calibration and validation of the numerical model. The investigated variables are the technique (manual stick arc (SMAW) and gas arc (GMAW) welding) and the joint shape (butt and T joint) for steel joints, in sound conditions and with artificial flaws. Numerical simulation of welding thermal transients was run to obtain the expected surface temperature fields and thermal behavior for different welding parameter configurations. Hardness measurement and micro-graphic analysis were performed to validate numerical simulation results. The real-time thermographic study of the weld pool gives direct indications of anomalies; local studies of the thermal transient and thermal profiles can detect some kind of flaws; microstructural analysis of Heat-Affected Zone (HAZ) and surrounding areas higlights the presence of austenite and martensite distribution which justifies the thermal transients and thermal profiles for different welding configurations. Comparing real-time IR acquisition of the welding process with simulated thermal contours of sound processes provides information of presence of some kind of flaws. Since most of the flaws are generated in the weld pool, it is possible to recognize anomalies directly from the thermal acquisitions or with post-processing the acquired data.

Vision-Based Soft Mobile Robot Inspired by Silkworm Body and Movement Behavior

Designing an inexpensive, low-noise, safe for individual, mobile robot with an efficient vision system represents a challenge. This paper proposes a soft mobile robot inspired by the silkworm body structure and moving behavior. Two identical pneumatic artificial muscles (PAM) have been used to design the body of the robot by sewing the PAMs longitudinally. The proposed robot moves forward, left, and right in steps depending on the relative contraction ratio of the actuators. The connection between the two artificial muscles gives the steering performance at different air pressures of each PAM. A camera (eye) integrated into the proposed soft robot helps it to control its motion and direction. The silkworm soft robot detects a specific object and tracks it continuously. The proposed vision system is used to help with automatic tracking based on deep learning platforms with real-time live IR camera. The object detection platform, named, YOLOv3 is used effectively to solve the challenge of detecting high-speed tiny objects like Tennis balls. The model is trained with a dataset consisting of images of Tennis balls. The work is simulated with Google Colab and then tested in real-time on an embedded device mated with a fast GPU called Jetson Nano development kit. The presented object follower robot is cheap, fast-tracking, and friendly to the environment. The system reaches a 99% accuracy rate during training and testing. Validation results are obtained and recorded to prove the effectiveness of this novel silkworm soft robot. The research contribution is designing and implementing a soft mobile robot with an effective vision system.

Real-time insight into the multistage mechanism of nanoparticle exsolution from a perovskite host surface

In exsolution, nanoparticles form by emerging from oxide hosts by application of redox driving forces, leading to transformative advances in stability, activity, and efficiency over deposition techniques, and resulting in a wide range of new opportunities for catalytic, energy and net-zero-related technologies. However, the mechanism of exsolved nanoparticle nucleation and perovskite structural evolution, has, to date, remained unclear. Herein, we shed light on this elusive process by following in real time Ir nanoparticle emergence from a SrTiO3 host oxide lattice, using in situ high-resolution electron microscopy in combination with computational simulations and machine learning analytics. We show that nucleation occurs via atom clustering, in tandem with host evolution, revealing the participation of surface defects and host lattice restructuring in trapping Ir atoms to initiate nanoparticle formation and growth. These insights provide a theoretical platform and practical recommendations to further the development of highly functional and broadly applicable exsolvable materials.

A real-time IR navigation system for pleural photodynamic therapy with a 3D surface acquisition system.

Photodynamic therapy (PDT) has been used intraoperatively to treat patients with malignant pleural mesothelioma. For the efficiency of PDT, it is crucial to deliver light doses uniformly. The current procedure utilizes eight light detectors placed inside the pleural cavity to monitor the light. An updated navigation system, combined with a novel scanning system, is developed to provide real-time guidance for physicians during pleural PDT to improve light delivery. The scanning system consists of two handheld three-dimensional (3D) scanners to capture the pleural cavity's surface topographies quickly and precisely before PDT so that the target surface can be identified for real-time light fluence distribution calculation during PDT. An algorithm is developed to further process the scanned volume to denoise for accurate light fluence calculation and rotate the local coordinate system into any desired direction for a clear visualization during the real-time guidance. The navigation coordinate system is registered to the patient coordinate system utilizing at least three markers to track the light source point position within the pleural cavity throughout the treatment. During PDT, the light source position, the scanned pleural cavity, and the light fluence distribution for the cavity's surface will be displayed in 3D and 2D, respectively. For validation, this novel system is tested using phantom studies with a large chest phantom and 3D-printed lung phantoms of different volumes based on a personal CT scan, immersed in a liquid tissue-simulating phantom with different optical properties, and treated with eight isotropic detectors and the navigation system.

Polythionourethane Thermoset Synthesis via Activation of Elemental Sulfur in an Efficient Multicomponent Reaction Approach

For the transition toward a safer and more sustainable production of polymeric materials, new synthetic concepts need to be developed. Herein, we describe a catalytic, solvent-free synthesis approach for novel thionourethane thermoset materials, in which the diisothiocyanate reactant is generated in situ via a sulfurization of isocyanides with elemental sulfur, preventing the exposure and handling of the diisothiocyanate. In this one-pot procedure, castor oil fulfills a dual role: (i) acting as the solvent for the in situ diisothiocyanate synthesis in the first step and (ii) reacting as the polyol component in the subsequent thionourethane thermoset formation. The kinetics of the consecutive two steps were studied in detail via real-time IR measurements, and the thermoset crosslinking step was found to be thermally triggerable after the diisothiocyanate reactant is quantitatively formed, enabling high control over the curing process of the system. Differential scanning calorimetry, thermogravimetric analysis, and rheological measurements were performed to investigate the thermal and mechanical properties of the novel thionourethane thermosets and then compared to analogous polyurethane materials. Our results demonstrate an unprecedented approach for thermoset synthesis via an in situ reagent synthesis, i.e., the generation of isothiocyanates from isocyanides by catalytic activation of elemental sulfur, and subsequent thermally triggerable thermosetting with a polyol, resulting in materials with appealing properties.

Reaction Analysis and Process Optimization with Online Infrared Data Based on Kinetic Modeling and Partial Least Squares Quantitation.

In-situ Fourier transform infrared (FT-IR) spectroscopy has been recognized as an important technology for online monitoring of chemical reactions. However, analysis of the real-time IR data for identification and quantification of uncertain reactants or intermediates is often ambiguous and difficult. Here, we propose an analysis algorithm based on reaction kinetic modeling and the chemometric method of partial least squares (PLS) to comprehensively and quantitatively study reaction processes. Concentration profiles and apparent kinetic parameters can be simultaneously calculated from the spectral data, without the demand of complicated analysis on characteristic absorbance peaks or tedious sampling efforts for multivariate modeling. Paal-Knorr reactions and glyoxylic acid synthesis reactions were selected as typical reactions to validate the algorithm. A lack of fit of the Paal-Knorr reaction spectra was less than 2.5% at various conditions, and the absolute errors between the predicted values and HPLC measurement of glyoxylic acid synthesis were less than 6% during the reaction process. Moreover, the reaction kinetic models extracted from FT-IR data were used to simulate reaction processes and optimize the conditions in order to maximize product yields, which proved that this analysis method could be used for process optimization.

Mechanism and kinetic study of Paal-Knorr reaction based on in-situ MIR monitoring

An in-depth understanding of reaction processes is beneficial to the development and quality control of chemical products. In this work, the mechanism and kinetics of the Paal-Knorr reaction for pyrrole derivatives are thoroughly studied using in-situ Fourier transform infrared (FTIR) spectroscopy. The hemiacetal amine intermediate, reactants, and products were identified and quantified by the treatment of real-time infrared spectra via chemometrics method and two-dimensional correlation spectroscopy (2DCOS) technique. Based on the IR quantitative models, influences of operating conditions on reaction processes were investigated, and the reaction kinetic model was built with kinetic parameters of two rate-limiting reaction steps calculated. This approach of analysis on the in-situ FTIR data demonstrated the ability to extract useful information on reaction components, especially the intermediate spectrum, from the confounding real-time IR data. The in-situ FTIR monitoring combined with the IR analysis methods is proved as a powerful tool for revealing the reaction mechanism and kinetics.

Functionalisation of esters via 1,3-chelation using NaOtBu: mechanistic investigations and synthetic applications

Unusual nucleophilic behavior of a metal t-butoxide in a transesterification reaction was demonstrated by NMR and real-time IR spectroscopies and deuterium-labeling experiments.

Tannic acid functionalized UV-curable carbon nanotube: Effective reinforcement of acrylated epoxidized soybean oil coating

In this study, an efficient method of preparing tannic acid functionalized UV-curable carbon nanotube for the reinforcement of acrylated epoxidized soybean oil coating is presented. A photoactive tannic acid (pTA) was prepared by the ring opening reaction of tannic acid (TA) and glycidyl methacrylate (GMA), and then used to non-covalently functionalize carbon nanotubes via π-π interactions to obtain a novel kind of tannic acid functionalized UV-curable carbon nanotube (pTA/MWCNTs). The pTA/MWCNTs was fully characterized and subsequently incorporated into acrylated epoxidized soybean oil (AESO) covalently via UV curing technology. A series of epoxidized soybean oil acrylate composite with different content of pTA/MWCNTs were prepared and the properties of pTA/MWCNTs/AESO composite materials were investigated. Real-time IR and ATR-FTIR were used to monitor the double bond conversion and deep curing of pTA/MWCNTs/AESO coating. The mechanical properties of UV-cured films were evaluated by tensile testing. The results showed that the introduction of pTA/MWCNTs effectively enhanced the physical and mechanical properties of AESO. And when the loading of pTA/MWCNTs is 0.8 wt%, optimal reinforcing effect for AESO matrix was observed with the tensile strength and modulus of the pTA/MWCNTs/AESO composite improved by 109% and 409%, respectively. In great contrast, the introduction of pristine MWCNTs without modification leads to the incomplete curing of AESO and thus a great decrease in the mechanical performance, demonstrating the important role of modification by pTA.

Frequency-Domain Power Delivery Network Self-Characterization in FPGAs for Improved System Reliability

Modern field-programmable gate arrays (FPGAs) operate at a core voltage around 1 V and therefore even small voltage fluctuations lead to timing violations and logic errors. The power delivery network (PDN) between the voltage regulator and the FPGA core must be carefully designed to achieve a low output impedance over a broad range of frequencies. Simulation tools are commonly used to estimate the impedance, however, they do not account for aging, component variations, and inaccurate modeling of parasitic elements, all of which lead to PDN design deviation. In this paper, two schemes are presented: first, to extract the dc resistance in the power delivery path, and second, to identify the high impedance frequency band(s) in the PDN. The embedded impedance extraction tool is synthesized within the FPGA load, in coordination with a mixed-signal current-mode dc–dc converter. A new self-calibrated carry-chain-based analog-to-digital converter (CC-ADC) is used for high-speed sampling of the core voltage. The proposed schemes are demonstrated on an Intel Cyclone IV FPGA board. Real-time IR -drop compensation is shown to eliminate logic errors in an finite impulse response filter application. It is also shown that the fail/pass map of a crossbar application matches well with the extracted impedance profile versus voltage and frequency. By modifying the PDN based on the extracted results, the voltage operating range and reliability of the crossbar application are greatly extended.

Bio-based reactive diluent derived from cardanol and its application in polyurethane acrylate (PUA) coatings with high performance

A UV-curable cardanol-based monomer (ECGE) was prepared using cardanol and epichlorohydrin, followed by epoxidation of the unsaturation in alkyl side chains of cardanol segments. After its chemical structure was confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance (1H NMR), ECGE was used as a reactive diluent to copolymerize with castor oil-based polyurethane acrylate (PUA) and a series of UV-curable coatings were prepared. Results showed that the viscosity and volume shrinkage of the UV-curable PUA system decreased significantly after the introduction of cardanol-based monomer while maintaining reasonably high bio-renewable contents; when containing 50% of ECGE, the biomass content reaches 66.2%, which is 1.41 times that of pure resin. In addition, the coating properties were evaluated to determine hardness, adhesion, flexibility, and water resistance. The properties of UV-curable thermoset were also studied using tensile testing, dynamic mechanical thermal analysis, and thermogravimetric analysis. The cardanol-based coatings showed excellent adhesion, flexibility, medium hardness, and enhanced char yield although tensile strength, tensile modulus and glass transition temperatures were somewhat diminished. All these performances can be attributed to the unique architectures of ECGE that combined the structural features of rigid benzene ring and long flexible alkyl chains. The UV-curing behavior was determined using real-time IR, and the results indicated that the conversion of unsaturated bond was increased with more concentration of ECGE.

High-Performance Soybean-Oil-Based Epoxy Acrylate Resins: “Green” Synthesis and Application in UV-Curable Coatings

Novel soybean-oil-based (SBO-based) epoxy acrylate (EA) resins were developed via ring-opening reaction of epoxidized soybean oil (ESO) with hydroxyethyl methacrylated maleate (HEMAMA) precursor, a synthesized unsaturated carboxylic acid having two active C═C groups and a side methyl group. Experimental conditions for the synthesis of the precursor and the SBO-based EA (ESO-HEMAMA) product were studied, and their chemical structures were confirmed by FT-IR, 1H NMR, 13C NMR, and gel permeation chromatography. Subsequently, the volatility of HEMAMA was studied and compared with acrylic acid (AA). Furthermore, gel contents and ultimate properties of the UV-cured ESO-HEMAMA resins were investigated and compared with a commercial acrylated ESO (AESO) resin. At last, UV-curing behaviors of the SBO-based EA resins were determined by real-time IR. It was found that the HEMAMA precursor showed much lower volatility than AA, and the optimal pure ESO-HEMAMA resin possessed a C═C functionality up to 6.02 per ESO and ...

Castor oil-based polyfunctional acrylate monomers: Synthesis and utilization in UV-curable materials

A new polyfunctional acrylate monomer (COPERAA) was synthesized from castor oil and utilized as a sustainable reactive diluent for UV-curable materials. Firstly, experimental conditions for the synthesis of the monomer were optimized and its chemical structures were confirmed by FT-IR, 1H NMR, and ESI–MS. Subsequently, the effect of COPERAA on biobased content, viscosity, and volumetric shrinkage of the obtained AESO resins were studied. After that the effect of COPERAA on thermal, mechanical, coating, and swelling properties of the resulting UV-cured bioresins were investigated. Furthermore, UV-curing behaviors of the resultant bioresins were evaluated by real-time IR. Compared with the petroleum-based trimethylolpropane triacrylate (TMPTA) diluent, the biobased COPERAA diluent showed better performance on the biobased content, volumetric shrinkage, adhesion, and final CC conversions of the resulting AESO materials and better compatibility with the AESO prepolymer. Therefore, the developed oil-based diluent shows promise to be applied in UV-curable materials.

Use of cardanol-based acrylate as reactive diluent in UV-curable castor oil-based polyurethane acrylate resins

A biobased diluent, cardanyl acrylate (CA), was synthesized from cardanol and used to modify a castor oil-based polyfunctional polyurethane acrylate (PUA) resin. Firstly, chemical structure of CA was characterized by FT-IR, 1H NMR, and 13C NMR. Subsequently, the effect of CA’s content on the biobased content, viscosity, and volumetric shrinkage of the obtained bioresins were studied and compared with the petroleum-based hydroxyethyl acrylate (HEA) diluent. Moreover, ultimate properties of the UV-cured biomaterials such as thermal, mechanical, coating, swelling, and hydrophobic properties were investigated. Finally, UV-curing kinetics of the resulting bioresins were determined by real-time IR. By the addition of CA, the biobased content of the resulting bioresins were improved and the viscosity and volumetric shrinkage were reduced. For example, the obtained bioresin containing 30% of CA possessed a biobased content of 62.8% and volumetric shrinkage of 9.51%, which were clearly better than those of the bioresin with 30% of HEA (50.8% and 21.94%), respectively. Furthermore, many other properties of the UV-cured biomaterials, such as thermal stability, coating’s hardness and adhesion, and hydrophobic properties, were improved by the incorporation of CA. The final CC conversions of the resulting bioresins were also enhanced by the addition of CA. Hence, the cardanol-based diluent showed good potential in the development of UV-curable coatings.

Effect of Superbasic Ionic Liquids on the Synthesis of Dendritic PolyaminesviaAza-Michael Addition Reaction

Catalytic effect of selected superbasic ionic liquids on the yield and selectivity of aza-Michael addition of ethylenediamine and ammonia to acrylonitrile was investigated. The reactions were performed in calorimetric reactor equipped with RT-IR probe (real-time IR), where all energy changes associated with chemical reactions and physical transformations were monitored. Catalytic activity of selected superbasic ionic liquids in aza-Michael addition ethylenediamine and ammonia to acrylonitrile were determined and obtained polynitriles were then hydrogenatated to final three- and four-directional dendritic polyamines. The products were characterized by instrumental analytical methods, including 1H-NMR, GC/MS, FTIR and DSC. Application of superbasic ionic liquids positively influenced both the yield of aza-Michael addition and selectivity to fully branched products.

A DFT-Based Computational-Experimental Methodology for Synthetic Chemistry: Example of Application to the Catalytic Opening of Epoxides by Titanocene.

A novel DFT-based Reaction Kinetics (DFT-RK) simulation approach, employed in combination with real-time data from reaction monitoring instrumentation (like UV-vis, FTIR, Raman, and 2D NMR benchtop spectrometers), is shown to provide a detailed methodology for the analysis and design of complex synthetic chemistry schemes. As an example, it is applied to the opening of epoxides by titanocene in THF, a catalytic system with abundant experimental data available. Through a DFT-RK analysis of real-time IR data, we have developed a comprehensive mechanistic model that opens new perspectives to understand previous experiments. Although derived specifically from the opening of epoxides, the prediction capabilities of the model, built on elementary reactions, together with its practical side (reaction kinetics simulations of real experimental conditions) make it a useful simulation tool for the design of new experiments, as well as for the conception and development of improved versions of the reagents. From the perspective of the methodology employed, because both the computational (DFT-RK) and the experimental (spectroscopic data) components can follow the time evolution of several species simultaneously, it is expected to provide a helpful tool for the study of complex systems in synthetic chemistry.

High biocontent natural plant oil based UV-curable branched oligomers

Abstract A new, green approach to improve the performance and biorenewable content of natural plant oil based UV-curable materials is presented. A novel kind of soy-based UV-curable branched oligomer (ACSO) was synthesized by chemically introducing cashew nutshell liquid (CNL) onto the epoxidized soybean oil (ESBO) backbone, followed by epoxidization and acrylation. The synthesized ACSO were used to produce UV-curable films and coatings. The UV-curing behavior of ACSO was investigated using real-time IR. The properties of UV cured films were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, and nanoindentation technique. Compared to coating from acrylated epoxidized soybean oil (AESO), ACSO based coating exhibited higher impact resistance, better crosshatch adhesion, and enhanced thermal and mechanical properties. Meanwhile, high biorenewable content was maintained due to the biorenewable character of CNL in ACSO. The improved coating properties can be attributed to the incorporated aromatic ring from CNL and multi-branched structure of ACSO. This approach provided a new direction to the future development of advanced bio-based UV-curable oligomers with reasonably high biorenewable content.

Material design and photo-regulated hydrolytic degradation behavior of tissue engineering scaffolds fabricated via 3D fiber deposition.

An ideal behavior of a tissue engineering scaffold is that it degrades and reshapes at a rate that matches the formation of new tissues. However, this ideal situation may not occur as the scaffold often undergoes too slow or too fast degradation. To test the promise of the active control of scaffold degradation, in this work, a photo/water dual-degradable porous scaffold was designed and fabricated using a 3D fiber deposition (3DF) system from a linear biopolymer (named PLANB) that combined the o-nitrobenzyl linkages and hydrolysable ester bone in the polymer chains. The chemical structure, molecular weight and polydispersity of PLANB were characterized by IR, NMR, GPC and MALDI-TOF-MS. The thermal properties of PLANB evaluated by DSC and TGA assays enabled a 3DF printing at the temperature around its melting point without chemical changes. The introduction of a real-time IR (RTIR) technique not only facilitated the determination of photolysis kinetics and quantum yield, but also enabled the capture of intermediate products during the photo-cleavage process of PLANB scaffolds. A minute-scale daily photolysis combined with a continuous hydrolysis process was implemented to test the photo-regulated hydrolytic degradation behavior of PLANB scaffolds in vitro, and the results obtained from both the SEM image and the mass loss profile demonstrated a porous-void microstructure along the strands of scaffolds and an apparent increase of the mass loss amount compared with the control group without photo-irradiation. Furthermore, PLANB scaffolds showed low cytotoxicity to L929 cells and performed well in promoting cell adhesion. It can therefore be concluded that such scaffolds have great potential in offering a diverse range of control over degradation kinetics of tissue engineering scaffolds to be tailored to individual tissue regeneration situations.

Crystal structure, computational studies, and stereoselectivity in the synthesis of 2-aryl-thiazolidine-4-carboxylic acids via in situ imine intermediate

ABSTRACTThis article presents the synthesis of (2R/2S,4R)-2-aryl-thiazolidine-4-carboxylic acids via nucleophilic addition of L-Cysteine on aromatic aldehydes involving a yield and time-effective room temperature reaction in an aqueous DMSO medium in the presence of NaHCO3 as a base. The synthesized diastereomers were spectroscopically characterized and quantified for diastereomeric excess by liquid chromatography-mass spectrometry analysis. The impact of the type and position of substituent in aromatic aldehydes on reaction time, % yield, 1H NMR shift at newly formed chiral center [C(2)-H], and diastereomeric excess (de%) have been investigated. A plausible mechanism for stereoselectivity via an in situ imine intermediate is proposed using real-time IR monitoring of the synthetic reaction based on the significant signals at 1597, 1593 cm−1 for imine (C=N) stretching. The imine mechanism for stereoselectivity was further supported by NMR studies of azomethine 13C NMR signals at 159, 160 δ ppm and by the single crystal structure of hitherto unknown (2S,4R)-3-(tert-butoxycarbonyl)-2-(2-hydroxyphenyl)thiazolidine-4-carboxylic acid (3a) obtained as a major diastereomer in the synthesis of the butyloxy carbonyl (BOC) derivative of (2R/2S,4R)-2-(2-hydroxyphenyl)thiazolidine-4-carboxylic acid. The significant ortho-OH effect of phenolic hydroxyl group leading to strong hydrogen bondings plays a vital role in the formation of 2S,4R BOC derivative stereoselectively. The frontier molecular orbitals, possible electronic excitations, IR band characterizations, and reactivity parameters of newly reported compound (3a) have been predicted using quantum chemical descriptors from density functional theory. The theoretical exploration of experimental spectra using time-dependent DFT indicated a (π–π*) transition between HOMO and LUMO in the ultraviolet region.

基于物理模型的战场烟幕实时红外仿真

基于物理模型的战场烟幕实时红外仿真