IR Irradiation Research Articles

Identification of HOC•HC(O)H, HOCH2C•O, and HOCH2CH2O• Intermediates in the Reaction of H + Glycolaldehyde in Solid Para-Hydrogen and Its Implication to the Interstellar Formation of Complex Sugars.

Glycolaldehyde [HOCH2C(O)H, GA], the primitive sugar-like molecule detected in the interstellar medium (ISM), is a potential precursor for the synthesis of complex sugars. Despite its importance, the mechanism governing the formation of these higher-order sugars from GA under interstellar circumstances remains elusive. Radical intermediates HOCH2CH2O• (1), HOCH2C•HOH (2), HOCH2C•O (3), HOC•HC(O)H (4), and O•CH2C(O)H (5) derived from GA could be potential precursors for the formation of glyceraldehyde (aldose sugar), dihydroxyacetone (ketose sugar), and ethylene glycol (sugar alcohol) in dark regions of ISM. However, the spectral identification of these intermediates and their roles were little investigated. We conducted reactions involving H atoms and the Cis-cis conformer of GA (Cc-GA) in solid p-H2 at 3.2 K and identified IR spectra of radicals Cc-HOCH2C•O (3) and Cc-HOC•HC(O)H (4) produced from H abstraction as well as closed-shell HOCHCO (6) produced via consecutive H abstraction of GA. In addition, Cc-HOCH2CH2O• (1) and C•H2OH + H2CO (7) were produced through the H addition and the H-induced fragmentation channels, respectively. In darkness, when only H-tunneling reactions occurred, the formation of (3) was major and that of (1) was minor. In contrast, during IR irradiation to produce H atoms with higher energy, the formation of (4) and C•H2OH + H2CO (7) became important. We also successfully converted most Cc-GA to the second-lowest-energy conformer Trans-trans-GA (Tt-GA) by prolonged IR irradiation at 2827 nm to investigate H + Tt-GA; Tt-HOCH2C•O (3'), Tt-HOC•HC(O)H (4'), HOCHCO (6), Tt-HOCH2CH2O• (1'), and C•H2OH + H2CO (7) were observed. We discuss possible routes for the formation of higher-order sugars or related compounds involving (7), (1), (3), and (4), but neither (2), which was proposed previously, nor (5) plays a significant role in H + GA. Such previously unreported rich chemistry in the reaction of H + GA, with four channels of three distinct types, indicates the multiple roles that GA might play in astronomical chemistry.

Effect of wavelength and liquid on formation of Ag, Au, Ag/Au nanoparticles via picosecond laser ablation and SERS-based detection of DMMP.

The present study investigates the effects of input wavelength (1064, 532, and 355 nm) and surrounding liquid environment (distilled water and aqueous NaCl solution) on the picosecond laser ablation on silver (Ag), gold (Au), and Ag/Au alloy targets. The efficacy of the laser ablation technique was meticulously evaluated by analyzing the ablation rates, surface plasmon resonance peak positions, and particle size distributions of the obtained colloids. The nanoparticles (NPs) were characterized using the techniques of UV-visible absorption, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Furthermore, NPs of various sizes ranging from 6 to 35 nm were loaded onto a filter paper by a simple and effective drop-casting approach to achieve flexible surface-enhanced Raman spectroscopy (SERS) substrates/sensors. These substrates were tested using a simple, portable Raman device to identify various hazardous chemicals (malachite green, methyl salicylate, and thiram). The stability of the substrates was also systematically investigated by determining the decay percentages in the SERS signals over 60 days. The optimized SERS substrate was subsequently employed to detect chemical warfare agent (CWA) simulants such as methyl salicylate (a CWA simulant for sulfur mustard) and dimethyl methyl phosphonate (has some structural similarities to the G-series nerve agents) at different laser excitations (325, 532, and 633 nm). A notably higher SERS efficiency for CWA simulants was observed at a 325 nm Raman excitation. Our findings reveal that a higher ablation yield was observed at IR irradiation than those obtained at the other wavelengths. A size decrease of the NPs was noticed by changing the liquid environment to an electrolyte. These findings have significant implications for developing more efficient and stable SERS substrates for chemical detection applications.

Silicon Optrode with a Micromirror‐Tip Providing Tunable Beam Profile During Infrared Neuromodulation of the Rat Neocortex

AbstractInfrared (IR) neuromodulation holds an increasing potential in brain research, which is fueled by novel neuroengineering approaches facilitating the exploration of the biophysical mechanism in the microscale. The group lays down the fundamentals of spatially controlled optical manipulation of inherently temperature‐sensitive neuronal populations. The concept and in vivo validation of a multifunctional, optical stimulation microdevice is presented, which expands the capabilities of conventional optrodes by coupling IR light through a monolithically integrated parabolic micromirror. Heat distribution in the irradiated volume is experimentally analyzed, and the performance of the integrated electrophysiological recording components of the device is tested in the neocortex of anesthetized rodents. Evoked single‐cell responses upon IR irradiation through the novel microtool are evaluated in multiple trials. The safe operation of the implanted device is also presented using immunohistological methods. The results confirm that shift in temperature distribution in the vicinity of the optrode tip can be controlled by the integrated photonic components, and in parallel with the optical stimulation, the device is suitable to interrogate the evoked electrophysiological activity at the single neuron level. The customizable and scalable optrode system provides a new pathway to tailor the location of the heat maximum during infrared neural stimulation.

NMR and X-ray diffraction conformational study of guanidines

Leishmaniasis is a neglected disease that affects regions such as South Asia, South Africa, and Latin America, less developed regions. The research proposed the conformational study of brominated guanidine compounds with potential antileishmanial activity using Nuclear Magnetic Resonance (NMR) and X-ray diffraction (XRD) techniques. The present study involves the brominated molecules LQOF-G2, LQOF-G30, LQOF-G35 and LQOF-G35-Br. The latter was synthesized by the reaction of LQOF-G35 with NBS under IR irradiation at 120 Watts of potency and dichloromethane as solvent by 12 h of exposition. The obtained results demonstrated the efficiency of the bromination method, since two bromine atoms entered the molecule. Furthermore, NMR analysis showed a conformational change from Z to E when compound LQOF-G35 was brominated to LQOF-G35-Br. This behavior was confirmed by a comparative XRD study of the LQOF-G35 and LQOF-G35-Br compounds. The antileishmanial activity of LQOF-G2 e LQOF-G35 motivated the synthesis of new brominated compounds LQOF-G30 e LQOF-G35-Br.

Easy but Efficient: Facile Approach to Molecule with Theoretically Justified Donor-Acceptor Structure for Effective Photothermal Conversion and Intravenous Photothermal Therapy.

To accelerate the pace in the field of photothermal therapy (PTT), it is urged to develop easily accessible photothermal agents (PTAs) showing high photothermal conversion efficiency (PCE). As a proof-of-concept, hereby a conventional strategy is presented to prepare donor-acceptor (D-A) structured PTAs through cycloaddition-retroelectrocyclization (CA-RE) reaction, and the resultant PTAs give high PCE upon near-infrared (NIR) irradiation. By joint experimental-theoretical study, these PTAs exhibit prominent D-A structure with strong intramolecular charge transfer (ICT) characteristics and significantly twisting between D and A units which account for the high PCEs. Among them, the DMA-TCNQ exhibits the strongest absorption in NIR range as well as the highest PCE of 91.3% upon irradiation by 760-nm LED lamp (1.2W cm-2). In vitro and in vivo experimental results revealed that DMA-TCNQ exhibits low dark toxicity and high phototoxicity after IR irradiation along with nude mice tumor inhibition up to 81.0% through intravenous therapy. The findings demonstrate CA-RE reaction as a convenient approach to obtain twisted D-A structured PTAs for effective PTT and probably promote the progress of cancer therapies.

Synergetic effect for highly efficient light-driven CO2 reduction by CH4 on Co/Mg-CoAl2O4 promoted by a photoactivation

The utilization of photothermocatalytic dry reforming of methane is shown to be an up-and-coming technology. However, reaching high fuel productivity at a comparatively low light intensity and effectively suppressing the side reactions of coking in the DRM process are still two tough difficulties. Under focused UV–vis–IR irradiation at a relatively low light intensity of 80.5 kW m−2, a nanostructure of Co/Mg-CoAl2O4 possesses excellent photothermocatalytic activity and a light-to-fuel efficiency of 34.2 % and a low carbon deposition rate compared to its reference catalyst without Mg2+ doping (Co/CoAl2O4). The improved photothermocatalytic activity and coking resistance of Co/Mg-CoAl2O4 mainly comes from the synergetic effect, including Mg2+ doping, the active lattice oxygen in CoAl2O4 also participating in the oxidation of carbon species, and strong light absorption properties of the Mg-CoAl2O4. The photoactivation promotes DRM on Co nanoparticles while significantly facilitates the C* oxidation by strongly adsorbed CO2 on doped Mg2+.

Biospinning of hierarchical fibers for a self-sensing actuator

Artificial muscles, skin, and flexible electronics all benefit from smart actuators. However, developing actuators with high self-driving/sensing capabilities, as well as the real-time feedback function, remains a difficult issue. Herein, we reported a hierarchical fiber actuator with a desirable function. The fiber actuator was created by parallel wet-spinning sodium alginate (SA) and polypyrene (PPy)/graphene oxide (GO) (PPy/GO), which was then twisted to form a hierarchical structure. The constructed hierarchical fiber actuator demonstrated IR irradiation (150 W) and humidity responsiveness (90RH%), as well as a real-time feedback function, allowing autonomous and remote control in difficult situations. Meanwhile, such fiber has a synergistic response to both IR and humidity, which have a strong linear relationship (y = -0.150x + 0.004 and y = -0.217x + 0.007), and can be used for remote controllable fixed-point transportation in complex environments as well as real-time detection feedback in fixed-point environments. The hierarchical fibers are easily incorporated into a variety of actuators and detecting devices, including a breathing sensor and a self-sensing weightlifter. In the field of artificial muscle functions, hierarchical fibers have the potential to be a significant building element for next-generation actuators.

Advancements in solar spectral irradiance measurements by the TSIS-1 spectral irradiance monitor and its role for long-term data continuity

The first implementation of NASA’s Total and Spectral Solar Irradiance Sensor (TSIS-1) launched on December 15th, 2017, and was integrated into the International Space Station (ISS) to measure both the total solar irradiance (TSI) and the solar spectral irradiance (SSI). The direct measurement of the SSI is made by the LASP Spectral Irradiance Monitor (SIM) and provides data essential to interpreting how the Earth system responds to solar spectral variability. Extensive advances in TSIS-1 SIM instrument design and new SI-traceable spectral irradiance calibration techniques have resulted in improved absolute accuracy with uncertainties of less than 0.5% over the continuous 200–2400 nm spectral range. Furthermore, improvements in the long-term spectral stability corrections provide lower trend uncertainties in SSI variability measurements. Here we present the early results of the TSIS-1 SIM measurements covering the first 5 years of operations. This time period includes the descending phase of solar cycle 24, the last solar minimum, and the ascending phase of solar cycle 25. The TSIS-1 SIM SSI results are compared to previous measurements both in the absolute scale of the solar spectrum and the time dependence of the SSI variability. The TSIS-1 SIM SSI spectrum shows lower IR irradiance (up to 6% at 2400 nm) and small visible increases (~0.5%) from some previous reference solar spectra. Finally, initial comparisons are made to current NRLSSI2 and SATIRE-S SSI model results and offer opportunities to validate model details both for short-term (solar rotation) spectral variability and, for the first time, the longer-term (near half solar cycle) spectral variability across the solar spectrum from the UV to the IR.

Polymer nanocomposite adhesives with internal nano-heaters to facilitate multilayer laminate separation

Laminating adhesives used in multilayer films present strong, irreversible adhesion that limits the produced packaging systems to single-use applications. From a sustainability point of view, the recovery of individual polymers after use is imperative and a pivotal step is to make this adhesion reversible via breakdown of the adhesive structure. This work describes a promising strategy based on the incorporation of graphene into thermoreversible adhesive resin formulations to trigger the rupture of the adhesive network by exposure to IR radiation. Graphene is a thermal absorber that abruptly heats up under irradiation and efficiently dissipates this heat to the surrounding environment causing the adhesive network to collapse, resulting in remarkable changes in its mechanical properties. In this study, graphene was incorporated at low concentrations (0.25–1 wt %) into solvent-free polyurethane adhesives containing thermoreversible moieties. The photothermal effect at different loadings was evaluated and the formulation displaying the best balance between photothermal effect and optical properties was selected. Furthermore, the effect of irradiation on cyclability, fluidity and mechanical properties of the graphene-containing adhesives is evaluated. Good cyclability was observed and samples with a graphene loading of 0.25 wt % and 11.5 wt % of thermoreversible bonds (TRB) showed the largest difference in elongation under IR irradiation with respect to the neat adhesive. Creep testing demonstrated that the strain of this sample increases by almost 200% after irradiation due to the breakdown of the three-dimensional adhesive network triggered by the photothermal effect of graphene.

Palladium-Catalyzed Suzuki−Miyaura cross-coupling reactions employing hydrazone-thioether ligands in aqueous media under IR-irradiation

An in situ catalytic system was generated based on hydrazone-thioether ligands and Pd(OAc)2. It provided excellent catalytic activity in the Suzuki-Miyaura cross-coupling reactions between aryl halides and arylboronic acids in aqueous medium and under IR irradiation. The resulting coupled products were obtained in short reaction times, with low catalyst loads and in good to excellent yields. Density functional theory based computations were applied to characterize the probable structure of the dimeric complex formed between the hydrazone and Pd(OAc)2, afterwards structure was confirmed by experimental analysis of IR and ESI mass spectrometry.

Ir Sensory Properties of Multilayer Nanocomposite CuO/CNPs Films Produced by Electroporetic Synthesis

Purpose. Formation and studying the sensory properties of multilayer nanocomposite electrophoretic CuO/CNPs films in the infrared range.Methods. Study of the morphology and size composition of CuO/CNPs nanocomposite films using atomic force microscopy and scanning electron microscopy; determination of the chemical composition using X-ray diffractometry, the study of sensory sensitivity under infrared irradiation with a fiber-optic laser source with a wavelength of λ = 1064 nm; study of the temporal characteristics of the induced photoelectromotive force using optoelectric measurements (ADC L-CARD E2010D) interfaced with a personal computer.Results. Nanocomposite CuO/CNPs films 0.1 to 1 µm thick were obtained by electrophoretic synthesis on a glass substrate. It has been established that CuO/CNPs nanocomposite films are formed due to the ordered structuring of carbon nanoparticles along the direction of the electric field under the action of electrophoretic forces. At the same time, due to the electrolytic process, a layer of copper oxide from metal electrodes is formed on the surface of the carbon particles. The limiting size of carbon particles was 50-70 nm, depending on the parameters of film production. A technique has been developed for producing multilayer CuO/CNPs composite films with a thickness of one to ten layers. It has been established that when the synthesized ten-layer nanofilms are irradiated with infrared radiation with an intensity of 75 mW/cm-2, the value of the photogenerated EMF reaches 122.5 mV.Conclusion. Multilayer nanocomposite CuO/CNPs films with infrared sensor properties were obtained. It has been established that with an increase in the thickness of the synthesized films from one to ten layers, the photo-EMF under IR irradiation with an intensity of 75 mW/cm-2 increases from 17 to 122.5 mV.

Two-photon lifetime-based photoconversion of EGFP for 3D-photostimulation in FLIM

Enhanced green fluorescence protein (EGFP) is a fluorescent tag commonly used in cellular and biomedical applications. Surprisingly, some interesting photochemical properties of EGFP have remained unexplored. Here we report on two-photon-induced photoconversion of EGFP, which can be permanently converted by intense IR irradiation to a form with a short fluorescence lifetime and spectrally conserved emission. Photoconverted EGFP thus can be distinguished from the unconverted tag by the time-resolved detection. Nonlinear dependence of the two-photon photoconversion efficiency on the light intensity allows for an accurate 3D localization of the photoconverted volume within cellular structures, which is especially useful for kinetic FLIM applications. For illustration, we used the two photon photoconversion of EGFP for measurements of redistribution kinetics of nucleophosmin and histone H2B in nuclei of live cells. Measurements revealed high mobility of fluorescently tagged histone H2B in the nucleoplasm and their redistribution between spatially separated nucleoli.

Effective UV–visible-infrared light-driven photothermocatalytic dry reforming of methane on Ni/Ni-MgO caused by a novel synergetic effect and photoactivation

Light-driven photothermocatalytic dry reforming of methane (DRM) is a promising technology which can efficiently convert two greenhouse gases of CO2 and CH4 into fuels and realize effective solar energy storage simultaneously. It is greatly challenging to achieve high fuel production rate with a relatively low light intensity and restrain the coking side-reactions that cause catalyst deactivation. Herein, a novel nanocomposite of Ni nanoparticles (NPs) loaded on Ni-doped MgO (Ni/Ni-MgO) was prepared. Very high production rate (r) of H2 and CO (82.78 mmol min−1 g−1 and 98.05 mmol min−1 g−1) as well as a light-to-fuel efficiency (η, 28.8%) are obtained with concentrated UV–vis IR irradiation at a relatively low light intensity (78.8 kw m−2). Ni/Ni-MgO displays excellent durability due to its very low coking rate of 2.46 × 10−3 gc h−1 g−1catalyst, reduced by 11.6 times as compared to that of a reference sample of Ni NPs loaded on MgO (Ni/MgO). This is attributed to a synergetic effect between Ni NPs and Ni-MgO, in which the active oxygen of Ni-doped MgO participates in the oxidation of carbon species as one of the rate-determining steps of DRM, thus facilitating DRM on Ni NPs and greatly improving coking resistance. A photoactivation is found to greatly reduce activation energy and thus enhances catalytic activity due to the substantial facilitation of carbon oxidation by light irradiation.

Synthesis of PEG-PPG-PEG templated polydopamine nanoparticles under intensified conditions: Kinetics investigation, continuous process design and demonstration for photothermal application

Polydopamine is a nature inspired functional material with promising applications in a plethora of fields due to its structural, chemical, and optical properties. While there is significant interest in the preparation of polydopamine based nanomaterials that take advantage of its properties, less attention has been given to the optimisation of the synthetic process, which typically involves the oxidative self-polymerisation of dopamine under basic pH and requires 24–72 h for reaction completion. The present work investigated the kinetics of polydopamine formation in the presence of Pluronic P-123 (PEG-PPG-PEG) micelles acting as a soft template, in low monomer concentrations (that promote particle growth instead of nucleation) as a function of temperature and pressure. Simultaneous increase of pressure and temperature (up to 50 °C and 5 bar O2) was found to significantly reduce the reaction time to 20–40 min without compromising the particle quality. Based on the results of the kinetic investigation, the polydopamine synthesis was translated into a continuous process utilising a millifluidic co-axial membrane reactor with a focus on ease of use, process conditions’ reproducibility and safety of operation. The reactor produced nanoparticles similar to the batch synthesis and resisted fouling (which is generally expected in a compact flow reactor) due to the action of the P-123 surfactant. Due to the nontoxic process that utilises only biocompatible materials and oxygen as the oxidising agent, and the melanin-like structure of polydopamine, photothermal heating of the synthesised nanoparticles under concentrated IR irradiation at 808 nm light was studied, as this can potentially be used for photo-induced hyperthermia. The hyperthermia threshold of 10 °C temperature increase at relatively low laser power settings (fluence 1.77 W/cm2) was achieved, making it a promising candidate for this application.

Influence of the activation method on the activity of the nickel catalyst

<p>The results of a comparative analysis of the influence of the activation method on the catalytic properties of a nickel diatomaceous earth catalyst during the conversion of isopropyl alcohol to acetone are presented. Studies of the activity of the catalyst in the reaction of gas-phase dehydrogenation of isopropyl alcohol were carried out on a flow-type laboratory installation at a temperature of 150-350ºC. The mechanical activation of the nickel diatomaceous earth catalyst was carried out in a planetary mill. Traditional activation included pre-heat treatment of nickel diatomaceous earth catalyst in an atmosphere of O<sub>2</sub> and H<sub>2</sub> at 250°C; IR radiation was carried out using an incandescent lamp. It is shown that the nature of the activator determines the features of the formed surface nickel complexes. The activity of samples of the nickel diatomaceous earth catalyst subjected to activation by thermal reduction and thermal oxidation, as well as IR irradiation, testified to the low efficiency of these methods. A comparison of the activity of industrial nickel diatomaceous earth catalyst samples subjected to different activation methods showed that processing of samples by thermal reduction and thermal oxidation slightly increases the yield of acetone. In contrast, the original catalyst's IR irradiation and mechanical activation decreased its activity. Thus, thermal reduction and oxidation methods are promising for further research to increase the industrial nickel diatomaceous earth catalyst activity in dehydrogenating isopropyl alcohol into acetone. </p>

Deep understanding of the dependence between Cu surface wettability and C-adsorption/desorption

The dependence between the surface wettability of hydrothermally-treated Cu and C-adsorption/desorption is unclear, which restricts further expanding the practical applications of the superhydrophobic surfaces obtained via hydrocarbon adsorption and developing promising reversible super-wettability transition methods. Herein, spectroscopic (Raman and XPS) and microscopic (FESEM, AFM, SKPM) characterization results reveal that the superhydrophobicity of the hydrothermal Cu foil surfaces with micro-scaled Cu oxides depends on the adsorption of volatile C-containing organic species and is independent of the types of Cu oxides. Theoretical calculation results manifest that the adsorptions of volatile C-containing organic species on Cu2O and CuO both belong to strong chemisorptions. Inspired by the as-established dependence between Cu surface wettability and adsorption/desorption of volatile C-containing organic species, we develop facile, cost-effective, and environmental-friendly methods for reversibly modulating Cu surface super-wettability, which are accomplished by storing the sample with micro-structured Cu oxide(s) in C-rich ambience to realize superhydrophobicity and heating the superhydrophobic sample via short-time IR irradiation to achieve superhydrophilicity. Moreover, these super-wettability reversible transition methods are proved to be effective for other materials.

Metal oxide composites for detoxification of chemical warfare agent (CWA) simulant with enhanced catalytic activity under IR irradiation

Toxic organophosphate-based nerve agents have become the deadliest agents used in battlefields and terrorist attacks because even their small amounts can cause permanent damage, even after medical treatment. Various catalysts have been developed for the destruction of nerve agents. Among them, metal oxide nanoparticles have become one of the most widely studied materials owing to their excellent stability, high reactivity, and non-toxicity. Herein, we designed and synthesized a photothermally active metal oxide catalyst for the decomposition of DMNP consisting of SBA-15 containing MgO, which is deposited on GO, achieving unprecedented results. Under IR-LED irradiation, MgO@SBA-15@GO was an effective catalyst for the degradation of DMNP, resulting in a 15 min half-life (t1/2) of DMNP in EtOH. GO was employed to convert the absorbed light from IR irradiation to heat. This constant photothermal conversion increases the reaction temperature, resulting in a faster reaction rate without the use of an external heat source. Remarkably, MgO@SBA-15@GO showed no significant change in photothermal catalytic activity even after five cycles of reuse, demonstrating the high stability of the material. The material prepared herein performed well as a photothermally active heterogeneous catalyst for the degradation of DMNP under IR-LED light, indicating great potential for metal oxide catalysts used in combination with photothermal materials for catalytic decomposition of nerve agents.

Fluid-like cathode enhances valuable biomass production from brewery wastewater in purple phototrophic bacteria.

The climate crisis requires rethinking wastewater treatment to recover resources, such as nutrients and energy. In this scenario, purple phototrophic bacteria (PPB), the most versatile microorganisms on earth, are a promising alternative to transform the wastewater treatment plant concept into a biorefinery model by producing valuable protein-enriched biomass. PPB are capable of interacting with electrodes, exchanging electrons with electrically conductive materials. In this work, we have explored for mobile-bed (either stirred or fluidized) cathodes to maximize biomass production. For this purpose, stirred-electrode reactors were operated with low-reduced (3.5 e-/C) and high-reduced (5.9 e-/C) wastewater under cathodic polarization (-0.4 V and -0.8 V vs. Ag/AgCl). We observed that cathodic polarization and IR irradiation can play a key role in microbial and phenotypic selection, promoting (at -0.4 V) or minimizing (at -0.8 V) the presence of PPB. Then, we further study how cathodic polarization modulates PPB biomass production providing a fluid-like electrode as part of a so-called photo microbial electrochemical fluidized-bed reactor (photoME-FBR). Our results revealed the impact of reduction status of carbon source in wastewater to select the PPB photoheterotrophic community and how electrodes drive microbial population shifts depending on the reduction status of such carbon source.

Spectroscopic and X-ray structural investigations of the active calcium preparation

Structural studies of calcium citrate obtained by IR irradiation of calcium carbonate and citric acid in various ratios by spectroscopic and X-ray structural analysis has been carried out. It is shown that in the obtained samples of calcium carbonate there are polymorphic states in the form of aragonite, vaterite, calcite, as well as ikaite and in calcium citrate complex calcium compounds with different coordination numbers are observed.

Study of heating kinetics and temperature fields of melon fruits under IR irradiation

This article is devoted to the study of heating kinetics, temperature fields, as well as determining the laws of non-stationary heat transfer processes during treatment of melon fruits with IR rays. These studies, in turn, make it possible to determine the heating time to the desired temperature under different radiation conditions, which is a necessary condition for achieving a positive effect of heat treatment in infrared radiation. At the same time, the study of temperature fields and heating kinetics is carried out in order to reach the optimal regime obtained in the treatment of melon fruits with IR rays as a result of planning the experiment. The optimization of the process shows that the most appropriate mode of heat treatment of melon fruits during drying is IR irradiation at an incident flux density of 23-24 kW/m2 in a pulsed mode: τ=95 (-40)+60 (-30)+60 sec. The analysis of heating kinetics and temperature field confirms the correct selection of the optimal modes obtained in controlling the process of treatment of melon fruits with IR rays and allows to establish the laws of heat-mass transfer.