Conventional IR Research Articles

Cosmic-ray-induced chemical processes in CH3OH, CH3NH2 and CH3OH:CH3NH2 ices. Conventional and novel IR spectroscopic analysis with VIZSLA

Cosmic-ray-induced chemical processes in CH3OH, CH3NH2 and CH3OH:CH3NH2 ices. Conventional and novel IR spectroscopic analysis with VIZSLA

RBP-DIP: Residual back projection with deep image prior for ill-posed CT reconstruction

The success of deep image prior (DIP) in a number of image processing tasks has motivated their application in image reconstruction problems in computed tomography (CT). In this paper, we introduce a residual back projection technique (RBP) that improves the performance of deep image prior framework in iterative CT reconstruction, especially when the reconstruction problem is highly ill-posed. The RBP-DIP framework uses an untrained U-net in conjunction with a novel residual back projection connection to minimize the objective function while improving reconstruction accuracy. In each iteration, the weights of the untrained U-net are optimized, and the output of the U-net in the current iteration is used to update the input of the U-net in the next iteration through the proposed RBP connection. The introduction of the RBP connection strengthens the regularization effects of the DIP framework in the context of iterative CT reconstruction leading to improvements in accuracy. Our experiments demonstrate that the RBP-DIP framework offers improvements over other state-of-the-art conventional IR methods, as well as pre-trained and untrained models with similar network structures under multiple conditions. These improvements are particularly significant in the few-view and limited-angle CT reconstructions, where the corresponding inverse problems are highly ill-posed and the training data is limited. Furthermore, RBP-DIP has the potential for further improvement. Most existing IR algorithms, pre-trained models, and enhancements applicable to the original DIP algorithm can also be integrated into the RBP-DIP framework.

DEVELOPMENT, CHARACTERIZATION AND PHARMACOKINETIC EVALUATION OF OPTIMIZED VILDAGLIPTIN SUSTAINED RELEASE MATRIX TABLET USING BOX-BEHNKEN DESIGN

Objective: The principal objective of this research was to develop and optimize cost-effective sustained-release Vildagliptin (VLN) tablets using the wet granulation method. Methods: The tablets were prepared by the non-aqueous wet granulation method. A Box-Behnken design was used to study the effect of the independent variables, i.e., HPMC K100 M, Eudragit RSPO and PVP K30, on the dependent variables swelling index, in vitro drug release at 8 and 12 h. The drug's physiochemical properties were investigated using ultraviolet (UV), Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC). The hardness, thickness, weight variation, content uniformity, swelling index, and in vitro drug release study of the formulated tablets were all evaluated. The optimized formulation Opt-VLD-SR was evaluated for pharmacokinetic parameters like AUC, Cmax, tmax and MRT. Results: The FTIR and DSC studies confirmed that no interaction occurred between the drug, polymers and excipients. The crystalline nature of VLN remained unchanged in the optimised formulation tablet, according to DSC studies. With the optimal concentration of both polymers, formulation Opt-VLN delayed drug release for up to 12 h. The formulated Optimized Sustained-release tablets (Opt-VLD-SR) showed significantly lower Cmax±3.01ng/ml) than conventional IR tablets (256.17±8.02ng/ml). In the pharmacokinetic study, the MRT for Optimized-VLD-SR is (7.40h) showed a better result than the Vildagliptin IR marketed product (3.70 h.), which leads to higher bioavailability of Vildagliptin. Conclusion: Sustained release tablets of VLN with a combination of diffusion and erosion-controlled drug release mechanisms have been successfully developed.

Monolayers of a thiacalix[3]pyridine-supported molybdenum(0) tricarbonyl complex on Au(111): characterisation with surface spectroscopy and scanning tunneling microscopy.

Deposition of dome-shaped metal-organic complexes on metallic surfaces to produce well-defined single site catalysts is a novel approach combining aspects of homogeneous and heterogeneous catalysis. In order to investigate the bonding of small molecules to such systems, a molybdenum(0) tricarbonyl complex supported by a thiacalix[3]pyridine is synthesized and deposited on Au(111) and Ag(111) surfaces by vacuum evaporation. The resulting mono- and submonolayers are investigated with surface spectroscopy and STM. All of these methods indicate a parallel orientation of the molybdenum complex with respect to the surface. The vibrational properties and frequency shifts of the adsorbed complexes with respect to the bulk are evaluated with the help of conventional IR and IRRA spectroscopy, coupled to DFT calculations. Compared to a similar Mo(0) tricarbonyl complex supported by an azacalixpyridine ligand, the title complex exhibits a higher stability in the bulk and adsorbed to surfaces which goes along with a lower reactivity towards oxygen.

Targeted MRI (tMRI) of Small Increases in the T<sub>1</sub> of Normal Appearing White Matter in Mild Traumatic Brain Injury (mTBI) Using a Divided Subtracted Inversion Recovery (dSIR) Sequence

In modelling studies targeted MRI (tMRI) of small increases in the T<sub>1</sub> of tissues using divided Subtracted Inversion Recovery (dSIR) sequences show ten or more times the contrast seen with conventional IR sequences. This may be particularly useful in imaging normal appearing white matter where there may be small changes in T<sub>1</sub> and/or T<sub>2</sub> in disease but these changes may be insufficient to produce useful contrast with conventional T<sub>2</sub>-weighted spin echo (T<sub>2</sub>-wSE) and T<sub>2</sub>-FLuid Attenuated Inversion Recovery (T<sub>2</sub>-FLAIR) sequences. In a case of recurrent mild Traumatic Brain Injury (mTBI), very extensive high contrast abnormalities were seen in white matter using a dSIR sequence that targeted small increases in T<sub>1</sub> in areas where no abnormality was apparent with T<sub>2</sub>-wSE or T<sub>2</sub>-FLAIR sequences. The increases in T<sub>1</sub> may be due to neuroinflammation and/or degeneration which produces the abnormalities seen on the dSIR images. tMRI of normal appearing white matter may have widespread application in clinical MRI of the brain.

Deep learning enables time-efficient soft tissue enhancement in CBCT: Proof-of-concept study for dentomaxillofacial applications

PurposeThe use of iterative and deep learning reconstruction methods, which would allow effective noise reduction, is limited in cone-beam computed tomography (CBCT). As a consequence, the visibility of soft tissues is limited with CBCT. The study aimed to improve this issue through time-efficient deep learning enhancement (DLE) methods. MethodsTwo DLE networks, UNIT and U-Net, were trained with simulated CBCT data. The performance of the networks was tested with three different test data sets. The quantitative evaluation measured the structural similarity index measure (SSIM) and the peak signal-to-noise ratio (PSNR) of the DLE reconstructions with respect to the ground truth iterative reconstruction method. In the second assessment, a dentomaxillofacial radiologist assessed the resolution of hard tissue structures, visibility of soft tissues, and overall image quality of real patient data using the Likert scale. Finally, the technical image quality was determined using modulation transfer function, noise power spectrum, and noise magnitude analyses. ResultsThe study demonstrated that deep learning CBCT denoising is feasible and time efficient. The DLE methods, trained with simulated CBCT data, generalized well, and DLE provided quantitatively (SSIM/PSNR) and visually similar noise-reduction as conventional IR, but with faster processing time. The DLE methods improved soft tissue visibility compared to the conventional Feldkamp-Davis-Kress (FDK) algorithm through noise reduction. However, in hard tissue quantification tasks, the radiologist preferred the FDK over the DLE methods. ConclusionPost-reconstruction DLE allowed feasible reconstruction times while yielding improvements in soft tissue visibility in each dataset.

Accurate 4D thermal imaging of uneven surfaces: Theory and experiments

Conventional IR thermography is basically a 3D imaging model: pixel position (2D) and temperature (1D). However, the surface roughness, which cannot be depicted by the 2D geometry imaging, may introduce significant error into the temperature measurement, especially in close range. Although there are some principle studies on this theme, quantitative tools for arbitrary-shaped surfaces is still lacking. In this work, we have developed an imaging system composed of a binocular camera using structured illumination and an IR camera to reconstruct 4D uneven surface thermal images. This 4D information includes the 3D geometry of the surface and the temperature mapping over it. Based on the highly accurate surface roughness image obtained, a meshed area calculation tool is used to establish a temperature self-correction module for rough/uneven surfaces, which include convex surface, concave surface or their combinations. The effective emissivity of convex as well as flat surface is easy to calculate, because is this case, there is no inter-radiation or reflection. On contrast, the determination of concave surface emissivity is still posed as a challenge. In this work, some theoretic gap was first filled and then the experimental verification was provided. The temperature-correction takes angle of view and emissivity calibration into account. The angle of view is relative to the position of the object point and the emissivity calibration is based on the 3D geometry of the uneven surfaces. An imaginary flat surface is used to provide an effective emissivity for a local roughness. Experimental results shows that without this temperatue-correction module, the deviations between IR thermography and thermocouple are from ∼2.35 °C (at 50 °C) to ∼4.96 °C (at 300 °C) and from ∼2.43 °C (at 50 °C) to ∼4.78 °C (at 300 °C), while after the correction, the deviations are from ∼0.12 °C (at 50 °C) to ∼0.20 °C (at 300 °C) and from ∼0.16 °C (at 50 °C) to ∼0.20 °C (at 300 °C). Utilizing the thermal imaging model for recorrection, the deviations are from ∼0.13 °C (at 50 °C) to ∼0.19 °C (at 300 °C) and from ∼0.16 °C (at 50 °C) to ∼0.19 °C (at 300 °C). This generalized solution paves the way for high-accuracy temperature measurement on complexly rough surface, especially for high temperature, at which the measuring deviation can be very large.

Utility of a Ferrocene Unit in a Cyclometallated Cp*Ir(III) Catalyst during Water Oxidation: Exploring Bimetallic Cooperativity

AbstractFerrocene functionalized 2‐phenylpyridine iridium(III) pentamethylcyclopentadienyl complex is synthesized and probed for oxygen evolution from water. The excellent activity of this system has been rationalized by proposing a Fe(III)/Ir(IV) transient intermediate where bimetallic redox synergism between the Fe and Ir centres possibly provide an alternative pathway rather than a conventional Ir(V) based cycle.

Synthesis and application of biomass-derived magnetic biochar catalyst for simultaneous esterification and trans-esterification of waste cooking oil into biodiesel: modeling and optimization

This work created, characterized, and used a magnetic biochar catalyst that is both eco-friendly and very effective. Sugarcane bagasse was selected as primary raw material for catalyst preparation, because it is renewable and ecofriendly biomass. Catalyst created by doping sugarcane bagasse biochar with magnetic material in the form of (FeSO4·7H2O). Thermogravimetric Analysis (TGA) and Fourier Transform Infrared spectroscopy (FTIR) were used to characterize the catalyst. In addition, physical and textural characteristics of the catalyst were identified and interpreted. The characterization outcome showed that the catalyst has good catalytic qualities. For the manufacturing of biodiesel, discarded cooking oil served as the primary feedstock. The experiment was created utilizing the Box–Behnken Design (BBD) technique. There are four variables with the following three levels each: temperature, methanol to oil ratio, catalyst concentration, and reaction time. 29 experiments in total were carried out. Using the RSM function, optimization was done. The optimal conditions for obtaining biodiesel yield—temperature, methanol to oil ratio, reaction time, and catalyst weight—were 43.597 °C, 9.975 mol/L, 49.945 min, and 1.758 wt%. A study of the produced biodiesel using a FTIR showed that the conventional biodiesel IR spectra were confirmed. All physiochemical characteristics found suggested the biodiesel complied with ASTM and EN norms. Overall, the synthesized catalyst had conducted simultaneous reactions in a single batch reactor and had demonstrated suitability for converting used cooking oil to biodiesel.

Engineering Iridium-Based Oxygen Evolution Reaction Electrocatalysts for Proton Exchange Membrane Water Electrolyzers

The electrocatalytic water splitting technology, especially proton exchange membrane water electrolyzers (PEMWEs), is one of the core hydrogen production technologies to achieve carbon-free energy cycling. However, high acid corrosion and anodic potential operating conditions pose serious challenges for the development of PEMWEs. It is urgent to explore highly active, durable, and compatible anodic catalysts for the complex oxygen evolution reaction (OER). Hitherto, iridium (Ir)-based electrocatalysts (IBCs) with trade-off catalytic activity and stability are the primary candidates for the OER. Yet, the continued huge consumption of expensive and scarce Ir species severely hinders the widespread deployment of PEMWEs. It is necessary to systematically understand the latest research progress in IBCs to guide the controllable construction of catalysts with low-Ir loading to meet industrial demands. In this review, the conventional OER catalytic mechanism and Ir species-related failure modes are introduced. Subsequently, four common classes of IBCs, including Ir-based metals, oxides, perovskites, and pyrochlores, as well as attempts to correlate structural features of catalysts with their performance are reviewed. Within this scenario, the actual performances of bright representative IBCs applied in practical PEMWEs are also discussed. At the end of this review, unresolved issues and challenges in the field are proposed with a view to formulating effective strategies to break the bottleneck of commercial deployment of PEMWEs.

AFM-IR for Nanoscale Chemical Characterization in Life Sciences: Recent Developments and Future Directions.

Despite the ubiquitous absorption of mid-infrared (IR) radiation by virtually all molecules that belong to the major biomolecules groups (proteins, lipids, carbohydrates, nucleic acids), the application of conventional IR microscopy to the life sciences remained somewhat limited, due to the restrictions on spatial resolution imposed by the diffraction limit (in the order of several micrometers). This issue is addressed by AFM-IR, a scanning probe-based technique that allows for chemical analysis at the nanoscale with resolutions down to 10 nm and thus has the potential to contribute to the investigation of nano and microscale biological processes. In this perspective, in addition to a concise description of the working principles and operating modes of AFM-IR, we present and evaluate the latest key applications of AFM-IR to the life sciences, summarizing what the technique has to offer to this field. Furthermore, we discuss the most relevant current limitations and point out potential future developments and areas for further application for fruitful interdisciplinary collaboration.

Africa’s International Relations and the Legend of ‘Common Positions’

Abstract IR scholars and analysts often view the African Union’s apparent deference to common positions with a collectivist lens. However, in this article, I argue that the legend of common African positions (CAPs) has not yet been animated, as African leaders do not always work collectively for structural and political reasons. Two significant factors complicate analysing Africa’s IR in Africa: first, Africa is not a monolith. With fifty-five states and numerous linguistic, cultural, and historical paths, there is more that is different than is the same. Second, conventional IR theories are rooted in Global North worldviews and are, therefore, not the most appropriate tool to study African countries’ collective decision-making. I focus on the United Nations as the site where the Africa Group’s successes and failures are saliently illustrated, specifically the Ezulwini Consensus. The Africa Group’s contestation within the various UN bodies, particularly with the UN Peace and Security Council, where they have long lobbied for representation, underscores the strength and structural obstacles to Africa’s collective action. Taking an interpretative approach and analysing from an epistemological and normative level, I offer an alternative lens through which to view the CAPs. Leaning on the philosophies of Ubuntu and Ujamaa, I propose a framework to explore the African Union’s process of developing common positions.

Honeycomb layered topology construction for exceptional long-wave infrared nonlinear optical crystals.

Nonlinear optical (NLO) crystals capable of efficient long-wave infrared (8-14 μm) laser output remain scarce, and the exploration of long-wave IR NLO materials with superior comprehensive optical performances is a momentous challenge. Herein, we develop two selenide-halide NLO crystals, Hg3AsSe4Br and Hg3AsSe4I, which are derived from the honeycomb layered topology of prototype GaSe. Remarkably, they exhibit not only strong SHG effects, suitable band gap, large birefringence, broad IR transparency range and low two-photon absorption coefficients but reinforced interlayer interaction and more benign crystal growth habit, compared to those of GaSe, indicating that they are promising long-wave IR NLO materials. Moreover, Hg3AsSe4I achieved better comprehensive optical properties than conventional IR crystals, GaSe, ZnGeP2, CdSe and AgGaSe2. The idea of honeycomb layered topology construction provides a material design heuristic to explore cutting-edge IR NLO materials.

Rapidly Modulated Wide‐Spectrum Infrared Source Made of Super Aligned Carbon Nanotube Film for Greenhouse Gas Monitoring

AbstractNon‐dispersive infrared (NDIR) gas monitoring has advantages of environment stability, convenient operation and maintenance, wide detection range, and multi‐gas‐detection capability. However, the conventional IR sources for NDIR gas monitoring, such as miniature lamps, microelectromechanical system (MEMS) light sources, and light‐emitting diodes (LEDs), can only work at narrow modulation frequency and spectral range, or require complicated design and fabrication, because of the constraint of materials and work principle. These issues cause low data acquisition rate, poor anti‐interference ability and limited gas compatibility to NDIR. Here, the super‐aligned carbon nanotube (SACNT) film is developed as an IR source in NDIR gas monitoring system. It has a wide spectral range (0.2–334 µm), a facile fabrication method, and can work up to a high frequency ≈150 kHz. A mechanical‐chopper‐free and wide‐concentration‐range monitoring equipment for CO2 and CH4 greenhouse gases is demonstrated with SACNT film IR source. The concentration ranges for CO2 and CH4 investigated in this paper are 0.0195–20.10% (v/v) and 0.10–17.11% (v/v), respectively. It can be easily applied to monitor other kinds of gases as well.

9/11 was an Instance of Transnational Balancing: An Intervention in Statist IR Theory

With the end of the Cold War and through the start of the 21st century, conventional IR theories were anticipating an eventual balancing against the United States. Puzzled when this phenomenon did not occur, balancing theorists engaged in a lively discussion, bringing with it the development of proposed alternative forms of balancing and a debate over whether the concept itself had perhaps outlived its relevance. This article reengages with this discussion, suggesting that many of the involved theorists were hampered by theoretical blinders based on statism, and that in fact balancing did occur, but in an unconventional manner and at the hands of an unexpected suspect: al Qaeda, a violent non-state actor, acting in a transnational manner. In this context, this article treats the 9/11 attacks of the violent Jihadist anti-Western movement as an instance of balancing against the hegemon, a successful one in that the Jihadists arguably aimed not at “winning,” but at revealing the superpower’s weaknesses so that others would subsequently join the balancing effort. By failing to view the Jihadists’ efforts as an ideological balancing effort, the United States responded with force rather than ideational counter-balancing. They waged a war instead of emphasizing efforts to separate the radical violent Jihadist perpetrators from the idea they were championing—a struggle in the name of Muslims/the downtrodden East against the United States—and thus allowing the challenger to rise into a position of "dissident" in the Muslim world, and, arguably, paving the path for today's state revisionist behaviors. The article proposes a framework based on traditionally state-based concepts of intent and impact/capacity to show how non-state actors can in fact balance superpowers and therefore should be incorporated into balancing theories, and presents the actions of the violent Jihadists as an example of transnational, ideational balancing—a phenomenon as real and consequential as state-balancing.

Promoting Oxygen Evolution Reaction Induced By Synergetic Geometric and Electronic Effects of Irco Thin-Film Electrocatalysts

The advancement of water electrolysis technology has seemingly plateaued. Further advances require new strategies to address the key limitations of the oxygen evolution reaction: high overpotential and low stability of electrode materials. Herein, we designed a nanoporous Ir3Co-core@IrO2-shell electrocatalyst with 5 and 3 times higher mass activity and 6 and 2 times higher activity−stability factors than conventional IrO2 nanoparticles and Ir nanoporous electrocatalysts, respectively. The origin of the performance enhancement in the Ir3Co-core@IrO2-shell electrocatalyst was revealed in computational density functional theory calculations. The residual Co after the dealloying process resulted in a down-shift of the d-band center position, thus weakening the −OH* adsorption energy. In addition, the electronic conductivity was enhanced by the three-dimensionally interconnected structure. Under high-current-density operating conditions, the Ohmic losses were reduced by the ultrafast charge transfer pathway provided by the metallic IrCo core.

CO2 quantification in silicate glasses using µ-ATR FTIR spectroscopy

Abstract A new method for measurements of high-CO2 concentrations in silicate glasses was established using micro–attenuated total reflectance (µ-ATR) Fourier transform infrared (FTIR) spectroscopy in the mid-IR (MIR) region. We studied two glass/melt compositions, namely leucitite and granite, to cover samples in which CO2 is dissolved as carbonate ions (CO32−) or as CO2 molecules (CO3mol). In the leucitite glasses a carbonate absorption doublet with maxima at 1510 and 1430 cm–1 has shown to clearly separate from aluminosilicate lattice vibrations at lower wavenumbers. Due to the lower sensitivity of the µ-ATR method, we were able to measure high-CO2 contents (cCO2 >0.5 wt%) in experimental silicate glasses that would only be measurable with great difficulties using established transmission MIR measurements due to detector linearity limit effects even with very thin sample wafers. The peak heights of the 1430 cm–1 ATR band (A1430), normalized to the integral of the T-O lattice vibrations (T = Si, Al, Fe) at about 930 cm–1 (Int930) show a linear trend with CO2 contents in the range 0.2–4.3 wt%, yielding a linear correlation with cCO2 (wt%) = 0.4394 ± 0.006·A1430·10000/Int930. The normalization of the CO2 related band to a lattice vibration accounts for variations in the quality of contact between ATR crystal and sample, which has a direct effect on signal intensity. In granitic glasses, where CO2 is dissolved as CO3mol only, the asymmetric stretching vibration at 2350 cm–1 overlaps with the signal of atmospheric, gaseous CO2. As the ATR signal of dissolved CO2 is very weak, the atmospheric signal may dominate the spectrum. Since the absorbance spectrum is calculated by division of the single-channel sample spectrum by a single-channel reference spectrum measured in air, keeping the laboratory and spectrometer atmosphere as constant as possible during spectral acquisition can resolve the problem. Nonetheless, a procedure to subtract the signal of remaining atmospheric CO2 may still be required for the spectral evaluation. We studied a series of 5 granitic glasses with CO3mol contents of 0.08 to 0.27 wt% and found an excellent linear relation between CO2 concentration and lattice vibration normalized ATR intensity of the 2350 cm–1 band: cCO2 (wt%) = 0.2632 ± 0.0016·A2350·10000/Int990. Although the CO3mol concentrations in our granitic glass series can still be analyzed without major difficulties by conventional transmission IR spectroscopy, our data demonstrate the potential of the ATR method for samples with higher CO2 contents or for samples where a high spatial resolution is required (melt inclusions, vesicular or partially crystallized glasses). The lower limits of the ATR method are approximately 0.2 wt% CO2 dissolved as carbonate groups or 0.1 wt% CO2 (or slightly less) dissolved in molecular form.

Improving the understanding and performance of clinical MRI using tissue property filters and the central contrast theorem, MASDIR pulse sequences and synergistic contrast MRI.

This paper updates and extends three previous papers on tissue property filters (TP-filters), Multiplied, Added, Divided and/or Subtracted Inversion Recovery (MASTIR) pulse sequences and synergistic contrast MRI (scMRI). It does this by firstly adding the central contrast theorem (CCT) to TP-filters, secondly including division with MASTIR sequences to make them Multiplied, Added, Subtracted and/or Divided IR (MASDIR) sequences, and thirdly incorporating division into the image processing needed for scMR to increase synergistic T1 contrast. These updated concepts are then used to explain and improve contrast at tissue boundaries, as well as to develop imaging regimes to detect and monitor small changes to the brain over time and quantify T1. The CCT is in two parts: the first part states that contrast produced by each TP is the product of the change in TP multiplied by the TP sequence weighting which is the first partial derivative of the TP-filter. The second part states that the overall fractional contrast is the algebraic sum of the fractional contrasts produced by each of the TPs. Subtraction of two IR sequences alone about doubles contrast relative to a conventional single IR sequence. Division of this subtraction can amplify contrast 5–15 times compared with conventional IR sequences. Dividing sequences can be problematic in areas where the signal is zero but this is avoided by dividing the difference in signal of two magnitude reconstructed IR sequences by the sum of their signals. The basis for the production of high contrast, high spatial resolution boundaries at white-gray matter junctions, between cerebral cortex and cerebrospinal fluid (CSF) and at other sites with subtracted IR (SIR) and divided subtracted IR (dSIR) sequences is explained and examples are shown. A key concept is the tissue fraction f, which is the proportion of a tissue in a mixture of two tissues within a voxel. Contrast at boundaries is a function of the partial derivative of the TP-filter, the partial derivative of the relevant TP with respect to f, and the partial derivative of f with respect to distance, x. Location of tissue boundaries is important for segmentation and is helpful in determining if inversion times have been chosen correctly. In small change regimes, the high sensitivity to small changes in T1 provided by dSIR images, together with the high definition boundaries, afford mechanisms for detecting small changes due to contrast agents, disease, perfusion and other causes. 3D isotropic rigid body registration provides a technique for following these changes over time in serial studies. Images showing high lesion contrast, high definition tissue and fluid boundaries, and the detection of small changes are included. T1 maps can be created by linearly scaling dSIR images.

Preparation of dipolar Y(III)-based monoporphyrinate complexes: conventional vs microwave-assisted reaction and theoretical IR study

Preparation of dipolar Y(III)-based monoporphyrinate complexes: conventional vs microwave-assisted reaction and theoretical IR study

Radioprotective effect of X-ray abdominal FLASH irradiation: Adaptation to oxidative damage and inflammatory response may be benefiting factors.

Ultrahigh dose-rate irradiation (FLASH-IR) was reported to be efficient in tumor control while reducing normal tissue radiotoxicity. However, the mechanism of such phenomenon is still unclear. Besides, the FLASH experiments using high energy X-ray, the most common modality in clinical radiotherapy, arerarely reported. This study aims to investigate the radiobiological response using 6 MV X-ray FLASH-IR or conventional dose-rate IR (CONV-IR). The superconducting linac of Chengdu THz Free Electron Laser (CTFEL) facility was used for FLASH-IR, a diamond radiation detector and a CeBr3 scintillation detector were used to monitor the time structure and dose rate of FLASH pulses. BALB/c nude mice received whole abdominal 6 MV X-ray FLASH-IR or CONV-IR, the prescribed dose was 15Gy or 10Gy and the delivered absolute dose was monitored with EBT3 films. The mice were either euthanized 24 h post-IR to evaluate acute tissue responses or followed up for 6weeks to observe late-stage responses and survival probability. Complete blood count, histological analyses, and measurement of cytokine expression and redox status were performed. The mean dose rate of>150Gy/s and instantaneous dose rate of>5.5 × 105 Gy/s was reached in FLASH-IR at the center of mice body. After 6 weeks' follow-up of mice that received 15Gy IR, the FLASH group showed faster body weight recovery and higher survival probability than the CONV group. Histological analysis showed that FLASH-IR induced less acute intestinal damage than CONV-IR. Complete blood count and cytokine concentration measurement found that the inflammatory blood cell counts and pro-inflammatory cytokine concentrations were elevated at the acute stage after both FLASH-IR and CONV-IR. However, FLASH irradiated mice had significantly fewer inflammatory blood cells and diminished pro-inflammatory cytokine at the late stage. Moreover, higher reactive oxygen species (ROS) signal intensities but significantly reduced lipid peroxidation were found in the FLASH group than in the CONV group in the acute stage. The radioprotective effect of 6 MV X-ray FLASH-IR was observed. The differences in inflammatory responses and redox status between the two groups may be the factors responsible for reduced radiotoxicities following FLASH-IR. Further studies are required to thoroughly evaluate the impact of ROS on FLASH effect.