Relative Intensity Ratio Research Articles

The influence of resonant light pulses on high harmonic generation in solids

Abstract We have theoretically studied the high harmonic generation (HHG) in solids driven simultaneously by a mid-infrared (MIR) laser and a high-order harmonic pulse with energy around the band gap between the valence band and conduction band. By adding this resonant harmonic light pulse with the relative intensity ratio of 4\%, the high-order harmonic emission from the crystal is enhanced by 1-2 orders of magnitude. The yield of HHG in solid increases monotonically with the relative strength of the resonant harmonic pulses. In addition, we also found that HHG dynamics from the $k$ channel around the boundary of the Brillouin zone can be selectively enhanced by adjusting the frequency of the resonant high-order harmonic pulse. The resonance-enhanced HHG and $k$ channel selection effect in solids is also investigated by using the three-band semi-conductor Bloch equation for HHG in ZnO. We also find that the harmonic in the plateau region driven by adding a resonant light field to the strong MIR driving field has less red-shifted compared with the case driven by the MIR driving field alone.

Scheme for generation of spatiotemporal optical vortex attosecond pulse trains

The realization of spatiotemporal vortex structure of various physical fields with transverse orbital angular momentum (OAM) has attracted much attention and is expected to expand the research scope and open new opportunities in their respective fields. Here we present theoretically the first, to the best of our knowledge, study on the generation of attosecond pulse trains featuring a spatiotemporal optical vortex (STOV) structure by a two-color femtosecond light field, with each color carrying transverse OAM. Through careful optimization of relative phase and intensity ratio, we validate the efficient upconversion of the infrared pulse into its tens of order harmonics, showing that each harmonic preserves a corresponding intact topological charge. This unique characteristic enables the synthesis of an extreme ultraviolet attosecond pulse train with transverse OAM. In addition, we reveal that ionization depletion plays an outsize role therein. Our studies pave the way for the generation and utilization of light fields with STOV in the attosecond regime.

Parathyroid gland identification and angiography classification using simple machine learning methods.

Near-infrared indocyanine green angiography allows experienced surgeons to reliably evaluate parathyroid gland vitality during thyroid and parathyroid operations in order to predict postoperative function. To facilitate equal performance between surgeons, we developed an automatic computational quantification method using computer vision that portrays expert interpretation of visualized parathyroid gland near-infrared indocyanine green angiographic fluorescence signals. Near-infrared indocyanine green-parathyroid gland angiography video recordings (Fluobeam® LX, Fluoptics, Grenoble-part of Getinge-Göteborg) from patients undergoing endocrine cervical surgery in a high-volume unit were used for model development. Computation (MATLAB, Mathworks, Ireland) included segmentation-identification of the parathyroid gland (by autofluorescence), image stabilization (by linear translation) and adjusted time-fluorescence intensity profile generation. Relative upslope and maximum intensity ratios then trained a simple logistic regression model based on expert interpretation and outcome (including hypoparathyroidism), with subsequent unseen testing for validation. The model was trained on 37 patient videos (45 glands, 29 judged well perfused by parathyroid gland angiography experts), achieving feature data separation with 100% accuracy, and tested on 22 unseen videos (27 glands, 15 judged well perfused), including four in real time. Segmentation-guided parathyroid gland detection correctly identified all parathyroid glands during unseen testing along with three additional non-parathyroid gland regions (90% positive predictive value). Subsequent time-fluorescence intensity profile extraction with vitality prediction was shown feasible in all cases within 5 min, with a 96.3% model accuracy (sensitivity and specificity were 93.3 and 100% respectively) when compared with expert judgement. Automatic parathyroid gland perfusion quantification using simple machine learning computational methods discriminates parathyroid gland perfusion in concordance with expert surgeon interpretation, providing a means for near-infrared indocyanine green-parathyroid gland signal evaluation.

Toward Accurate Photoluminescence Nanothermometry Using Rare-Earth Doped Nanoparticles for Biomedical Applications.

ConspectusPhotoluminescence nanothermometry can detect the local temperature at the submicrometer scale with minimal contact with the object under investigation. Owing to its high spatial resolution, this technique shows great potential in biomedicine in both fundamental studies as well as preclinical research. Photoluminescence nanothermometry exploits the temperature-dependent optical properties of various nanoscale optical probes including organic fluorophores, quantum dots, and carbon nanostructures. At the vanguard of these diverse optical probes, rare-earth doped nanoparticles (RENPs) have demonstrated remarkable capabilities in photoluminescence nanothermometry. They distinguish themselves from other luminescent nanoprobes owning to their unparalleled and versatile optical properties that include narrow emission bandwidths, high photostability, tunable lifetimes from microseconds to milliseconds, multicolor emissions spanning the ultraviolet, visible, and near-infrared (NIR) regions, and the ability to undergo upconversion, all with excitation of a single, biologically friendly NIR wavelength. Recent advancements in the design of novel RENPs have led to new fundamental breakthroughs in photoluminescence nanothermometry. Moreover, driven by their excellent biocompatibility, both in vitro and in vivo, their implementation in biomedical applications has also gained significant traction. However, these nanoprobes face limitations caused by the complex biological environments, including absorption and scattering of various biomolecules as well as interference from different tissues, which limit the spatial resolution and detection sensitivity in RENP temperature sensing.Among existing approaches in RENP photoluminescence nanothermometry, the most prevalent implemented mechanisms either leverage the changes in the relative intensity ratio of two emission bands or exploit the lifetimes of various excited states. Photoluminescence intensity ratio (PLIR) nanothermometry has been the mainstream method owing to the readily available spectrometers for photoluminescence acquisition. Despite offering high temperature sensitivity and spatial resolution, this technique is restricted by tedious calibration and undesirable fluctuation in photoluminescence intensity ascribed to factors such as probe concentration, excitation power density, and biochemical surroundings. Lifetime-based nanothermometry uses the lifetime of a specific transition as the contrast mechanism to infer the temperature. This modality is less susceptible to various experimental factors and is compatible with a broader range of photoluminescence nanoprobes. However, due to relatively expensive and complex instrumentation, long data acquisition, and sophisticated data analysis, lifetime-based nanothermometry is still breaking ground with recently emerging techniques lightening its path.In this Account, we provide an overview of RENP nanothermometry and their applications in biomedicine. The architectures and luminescence mechanisms of RENPs are examined, followed by the principles of PLIR and lifetime-based nanothermometry. The in-depth description of each approach starts with its basic principle of accurate temperature sensing, followed by a critical discussion of the representative techniques, applications as well as their strengths and limitations. Special emphasis is given to the emerging modality of lifetime-based nanothermometry in light of the important new developments in the field. Finally, a summary and an outlook are provided to conclude this Account.

Effect of Sb2S3 sacrificial layer thickness on structural, optical and electrical properties of CuSbS2 films and investigation of diode parameters of CuSbS2/CdS heterojunctions

The ternary copper chalcogenides CuSbS2 (CAS) is found to have appealing optical and photovoltaic properties to be used as absorber layer in thin film solar cells. However, the difficulty to grow good quality CuSbS2 layer of micrometer thickness by chemical bath deposition method holds a big challenge. In this work, we reported the effect of incorporating Sb2S3 sacrificial layer of different thickness on structural, optical and electrical properties of CAS films. The X-ray diffraction results and Raman spectroscopic analysis confirm the formation of single-phase orthorhombic crystal structure for CuSbS2. The increase of Sb content in CAS films with the increase in deposition time of Sb2S3 layer has been reflected in the change in relative intensity ratio of characteristic Raman peaks as well as in diffraction peak profiles. The magnitude of defect states in terms of Urbach energy is decreased drastically by increasing Sb percentage in the films. A clear improvement in electrical properties of CAS films is observed with the decrease in Cu/Sb ratio. The carrier density is increased by one order of magnitude from 1016 to 1017 cm−3 and hole mobility increases from 1.14 to 4.87 cm2/Vs. The impact of Sb concentration on Scottky diode parameters of CAS/CdS heterojunction was studied by using thermionic emission model. Both the ideality factor and series resistance are decreased with the increase in Sb content. The J-V measurements reveal that the integration of Sb2S3 sacrificial layer improves the PV parameters such as fill factor, open circuit voltage, photocurrent and efficiency. The overall improvement in diode parameters can be ascribed to decrease in defect states, better film quality, absorber layer thickness and improved stoichiometry of CAS films.

Determination of the degree of crystallinity of polyphenylene sulfide composited with crystalline and non-crystalline fillers by applying the direct derivation method

A new procedure for determining the degree of crystallinity (DOC) has been recently proposed, and it has been verified using experimental and computer-generated powder diffractometry data [Toraya (2023). J. Appl. Cryst. 56, 1751–1763]. As an application to real materials like engineering plastics, this procedure is here applied to the DOC determination of plate-like polyphenylene sulfide (PPS) samples, composited with crystalline and non-crystalline fillers. The coexistence of partially crystallized polymer with non-crystalline fillers in target materials makes it difficult to separate the non-crystalline part of the partially crystallized polymer. This problem is here solved by the inverse application of the direct derivation (DD) method for quantitative phase analysis (QPA). The intensity–composition (IC) formula used in the DD method can derive the weight fractions of the individual components from just the total sums of observed intensities and the chemical composition data for these components [Toraya (2016). J. Appl. Cryst. 49, 1508–1516]. For the present purpose, the IC formula has been inversely applied to calculate the relative intensity ratios of individual components under the assumption that the chemical compositions and weight fractions of the respective components are known. The total halo intensity could then be separated into the non-crystalline part of the polymer and the non-crystalline filler. Analyzed results of PPS composites in four different DOCs are reported.

Pediatric diffuse intrinsic pontine glioma radiotherapy response prediction: MRI morphology and T2 intensity-based quantitative analyses.

An easy-to-implement MRI model for predicting partial response (PR) postradiotherapy for diffuse intrinsic pontine glioma (DIPG) is lacking. Utilizing quantitative T2 signal intensity and introducing a visual evaluation method based on T2 signal intensity heterogeneity, and compared MRI radiomic models for predicting radiotherapy response in pediatric patients with DIPG. We retrospectively included patients with brainstem gliomas aged ≤ 18 years admitted between July 2011 and March 2023. Applying Response Assessment in Pediatric Neuro-Oncology criteria, we categorized patients into PR and non-PR groups. For qualitative analysis, tumor heterogeneity vision was classified into four grades based on T2-weighted images. Quantitative analysis included the relative T2 signal intensity ratio (rT2SR), extra pons volume ratio, and tumor ring-enhancement volume. Radiomic features were extracted from T2-weighted and T1-enhanced images of volumes of interest. Univariate analysis was used to identify independent variables related to PR. Multivariate logistic regression was performed using significant variables (p < 0.05) from univariate analysis. Of 140 patients (training n = 109, and test n = 31), 64 (45.7%) achieved PR. The AUC of the predictive model with extrapontine volume ratio, rT2SRmax-min (rT2SRdif), and grade was 0.89. The AUCs of the T2-weighted and T1WI-enhanced models with radiomic signatures were 0.84 and 0.81, respectively. For the 31 DIPG test sets, the AUCs were 0.91, 0.83, and 0.81, for the models incorporating the quantitative features, radiomic model (T2-weighted images, and T1W1-enhanced images), respectively. Combining T2-weighted quantification with qualitative and extrapontine volume ratios reliably predicted pediatric DIPG radiotherapy response. Combining T2-weighted quantification with qualitative and extrapontine volume ratios can accurately predict diffuse intrinsic pontine glioma (DIPG) radiotherapy response, which may facilitate personalized treatment and prognostic assessment for patients with DIPG. Early identification is crucial for radiotherapy response and risk stratification in diffuse intrinsic pontine glioma. The model using tumor heterogeneity and quantitative T2 signal metrics achieved an AUC of 0.91. Using a combination of parameters can effectively predict radiotherapy response in this population.

Excellent Color Purity and Luminescence Thermometry Performance in Germanate Tellurite Glass Doped with Eu3+ and Tb3+

Germanate tellurite glasses doped with Eu3+ and Tb3+ were synthesized by the conventional melt-quenching method. There is no indication of the energy transfer between dopant ions in this host, but the co-dopants exhibit excellent color purity of 100% for Eu3+ and 80% for Tb3+. The co-doped glass exhibits yellow luminescence. The quantum yield of the Eu3+ emission is equal to 23% under 395 nm excitation. The thermal quenching of Eu3+ and Tb3+ luminescence occurs at different temperature ranges, which enables the thermal sensing properties of the material. The relative fluorescence intensity ratio (FIR) sensitivity of 0.16% K−1 was recorded in the wide range of temperatures spanning from −193 °C up to 0 °C. The temperature dependence of the decay times was also studied. The lifetime-based temperature sensitivity was determined to be 0.95% K−1 at 250 °C for Tb3+5D3 level emission and 0.3% K−1 at 225 °C for Eu3+5D1 level emission.

Double-hindered phenolic SiO2 composites with excellent oxidation resistance and thermal stability for enhanced thermal oxidation stability of PPS

In recent years, loading antioxidants onto inorganic nanoparticles has attracted increasing interest. However, the existing studies not only have low antioxidant loading efficiency, but also ignore the relationship between structural changes and antioxidant properties before and after antioxidant modification, greatly limiting the improvement of the antioxidant properties of composites and their application scope. In this work, we successfully prepared bis-hindered phenolic antioxidants containing silica hydroxyl groups (Bis-mAO) and loaded them onto silicon dioxide (SiO2) to get the nanocomposites (Bis-mAO-SiO2). The melt blending method further prepared the corresponding polyphenylene sulfide (PPS)/Bis-mAO-SiO2 composites. The results showed that the higher antioxidant loading and more suitable antioxidant structure made Bis-mAO-SiO2 possess excellent antioxidant properties. The prepared PPS/Bis-mAO-SiO2 composites remained stable under high temperatures and oxygen environments. Impressively, the maximum weight loss rate temperature of PPS/Bis-mAO-SiO2 was increased by 11.60 °C compared to that of PPS, and after accelerated thermal oxidation at 220 °C for 24 h, the relative intensity ratio between O and C of PPS/Bis-mAO-SiO2 only increased to 0.086, much lower than 0.132 for PPS. Moreover, the viscosity of PPS/Bis-mAO-SiO2 only increased by 29.05 % and 88.75 % after accelerated thermal oxidation at 220 °C for 12, 24 h. Compared, PPS's viscosity increased substantially by 79.22 % and 250.3 %, respectively. This meant that the Bis-mAO-SiO2 successfully achieved a synergistic integration of high antioxidant properties and thermal stability, implying that the work offered a strategy for fabricating high-temperature resistant antioxidant composites.

The mean relative signal intensity ratio (SIR) difference in patients undergoing dynamic contrast enhanced magnetic resonance imaging (DCE MRI) for diagnosis of pituitary microadenoma.

Objective: To determine the mean relative signal intensity ratio (SIR) difference in patients undergoing dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) for the diagnosis of pituitary microadenoma. Study Design: Descriptive, Cross-sectional study. Setting: Radiology Department, Allied Hospital I, Faisalabad. Period: 5th April 2021 to 4th October 2022. Material &amp; Methods: A total of 65 individuals undergoing magnetic resonance imaging with dynamic contrast enhancement of pituitary gland of any gender aged between 20 and 60 years were encompassed. Patients taking any medication (antipsychotics, anti-depressants, opiates or antiemetics), hepatic or renal failure, uncontrolled DM and hypothyroidism were excluded. Senior radiologist interpreted the DCE MR images. Pituitary microadenoma was assessed according to operational definition. For all patients, a region of interest (ROI) was defined on the area displaying varying enhancement, specifically identified as zone A. Amongst the entire patient population, a second ROI was made in the pituitary gland's normal-appearing tissue identified as zone B. Signal intensity time curves were created for all patients using both SIR T and SIR P, and the disparity between SIR T and SIR P was calculated. Relative SIR difference was calculated. Results: In my study, mean relative signal intensity ratio (SIR) difference in patients undergoing the utilization of DCE MRI for detecting pituitary microadenomas was 0.212 ± 0.181. The relative SIR difference on DCE MRI in patients with pituitary microadenoma was 0.35 ± 0.12 and in patients without pituitary microadenoma it was 0.03 ± 0.01. Conclusion: This study concluded that estimation of pre contrast T1 signal intensity ratio of a potentially abnormal lesion in dynamic contrast-enhanced MRI can enhance the accuracy of the diagnosis for locating microadenoma.

Cardiac magnetic resonance imaging detection of intramyocardial hemorrhage in patients with ST-elevated myocardial infarction: comparison between susceptibility-weighted imaging and T1/T2 mapping techniques.

Susceptibility-weighted imaging (SWI) and T1/T2 mapping can be used to detect reperfusion intramyocardial hemorrhage (IMH) in ST-segment elevation myocardial infarction (STEMI) patients. However, the sensitivity and accuracy of the SWI and T1/T2 mapping sequences were not systematically compared. The study aimed to evaluate image quality and diagnostic performance of SWI in patients with IMH, compared with T1/T2 mapping. A prospective study was conducted on consecutive acute STEMI patients who were recruited from January to July 2022. Within 2-6 days after reperfusion treatment, all patients underwent a 3T cardiac magnetic resonance (CMR) examination, including T2-weighted short-tau inversion recovery (T2W-STIR), T1/T2 mapping, and SWI. A total of 36 patients [age, 56.50±17.25 years; males, 83.33% (30/36)] were enrolled. The relative infarct-remote myocardium signal intensity ratio (SIinfarct-remote) and contrast-to-noise ratio (CNR) were calculated for each patient on T1/T2 mapping and SWI, and the difference between relative signal intensity-to-noise ratio (rSNR) in the IMH (rSNRIMH) was measured for IMH patients on T1/T2 mapping and SWI. SIinfarct-remote, CNR, and rSNRIMH were compared among the three sequences. Receiver operating characteristic (ROC) analyses were used to evaluate the diagnostic performance of three sequences by SIinfarct-remote and visual assessment. A total of 26 (72.22%) patients had IMH. Quantitatively, the SIinfarct-remote of three sequences had excellent diagnostic performance for detecting IMH [SWI area under the curve (AUC) =1.000, 95% confidence interval (CI): 1.000-1.000 vs. T1 mapping AUC =0.954, 95% CI: 0.885-1.000 vs. T2 mapping AUC =0.985, 95% CI: 0.955-1.000; SWI vs. T1 mapping, P=0.300; SWI vs. T2 mapping, P=0.188; T1 mapping vs. T2 mapping, P=0.302). Qualitatively, three sequences had similar performance on detecting IMH (SWI AUC =0.895, 95% CI: 0.784-1.000; T1 mapping AUC =0.835, 95% CI: 0.711-0.958; and T2 mapping AUC =0.855, 95% CI: 0.735-0.974; SWI vs. T1 mapping, P=0.172; SWI vs. T2 mapping, P=0.317; T1 mapping vs. T2 mapping, P=0.710). The rSNRIMH was highest in T1 mapping, followed by T2 mapping and SWI, but SWI had the highest CNR. SWI, as well as T1/T2 mapping, is a feasible and accurate approach for clinical diagnosis of IMH with excellent performance.

In Vitro Efficacy of Anti-HER2 CAR T-Cells in HER2 + BCP-ALL

Introduction: Around 30% of adults and 15% of children with B cell precursor acute lymphoblastic leukemia (BCP-ALL) relapse after a first line of treatment. The prognosis of these patients remains poor. Recent advances have involved targeted therapies with monoclonal antibodies and chimeric antigen receptor (CAR) T-lymphocytes (anti-CD19 CAR T-cells), which have produced very encouraging results in the high risk BCP-ALL setting(Maude et al. 2018). Nevertheless, half of these patients relapse after such therapies. In a third of cases, the disease no longer expresses the antigen previously targeted. New targets are therefore needed. HER2 is expressed in above one third of adult BCP-ALL (Chevallier et al. 2004) and 10% of childhood BCP-ALL (Camuset et al. 2021). HER2 expression is associated with chemoresistance and poor prognosis (Chevallier et al. 2004) (Camuset et al. 2021). The anti-HER2 antibody trastuzumab was prospectively tested in adult patients with HER2+ BCP-ALL, but yielded disappointing results (Chevallier et al. 2012). Anti-HER2 CAR T-cells could be an interesting alternative. Indeed, they have shown encouraging preclinical efficacy in solid tumors expressing HER2/neu (Budi et al. 2022). The present work was designed to evaluate, in vitro, the sensitivity of HER2+ BCP-ALL to anti-HER2 CAR engineered Epstein Barr virus (EBV) specific T-cells. Methods: DMSO-frozen cell-samples from 6 HER2+ BCP-ALL patients were available for this study. Patient characteristics are shown in Table 1. Blast cells from patient samples were preferred to cell lines in order to be more representative of BCP-ALL biology. level of HER2 expression on BCP-ALL samples was determined by flow cytometry and compared to the HER2 expressing breast-cancer cell line BT474. Anti-EBV cytotoxic T lymphocytes (CTLs), armed with a trastuzumab-based scFv-CH2-CH3-IgG2A-FcεRIγ chimeric receptor as previously described (Clémenceau et al. 2015) were used for long-term cytoxicity assays. For 4 samples, non-transduced anti-EBV CTLs were used as controls. Cytotoxic activity was assessed at a 3-to-1 effector-to-target ratio, in a flow cytometry assay. Cells were harvested at H0, H4 and H24 and stained with a viability stain (VS780). Further staining with anti-CD22 or anti-CD24 (depending on the BCP-ALL immunophenotype) and anti-CD3 antibodies allowed to characterize blast cells and CAR T-cells respectively. The study was approved by the local review board and two alive patients provided informed consent. Results: The level of HER2 expression by the 6 HER2+ BCP-ALL samples was variable with a median relative fluorescence intensity ratio (RFI) of 9 (range 1.8 to 16). These levels of expression were lower than those of the BT474 cell line (RFI= 79). No BCP-ALL lysis was observed when cells were incubated with trastuzumab alone (not shown). When co-cultured with non-transduced anti-EBV CTLs (CAR negative) (n=4), a decrease of residual viable BCP-ALL cells was observed at variable levels (Figure 1A). The lysis observed at 24h was possibly due to allogeneic recognition since anti-EBV CTLs were not autologous to the leukemias tested. Conclusion: This study first reveals that, although CTLs with TCRs restricted to EBV antigens and therefore intrinsically low allo-specificity were used, CAR-independent lysis was observed in 24 hours co-culture with BCP-ALL cells. These results underline the need for cautious interpretation of cytotoxicity test results in an allogeneic setting. Secondly, these preliminary data suggest that an anti-HER2 CAR T-cell approach could be promising for BCP-ALL even with weak antigen expression. Anti-EBV CTLs have already been used as a platform for CAR-engineered T-cells (Rossig et al. 2017). Should the cytotoxic activity of allogeneic EBV-CTL be proven to be specifically directed against BCP-ALL, the synergy between TCR and anti-HER2-CAR might be beneficial, and adoptive transfer of anti-HER2 CAR EBV CTLs could be a promising therapeutic option for patients with HER2+ BCP-ALL. * This research is funded by the non-profit organization Etoile de Martin/SFCE.

Nanohybrid Composites Based on TiO2 and Single-Walled Carbon Nanohorns as Promising Catalysts for Photodegradation of Amoxicillin.

In this work, applications of nanohybrid composites based on titanium dioxide (TiO2) with anatase crystallin phase and single-walled carbon nanohorns (SWCNHs) as promising catalysts for the photodegradation of amoxicillin (AMOX) are reported. In this order, TiO2/SWCNH composites were prepared by the solid-state interaction of the two chemical compounds. The increase in the SWCNH concentration in the TiO2/SWCNH composite mass, from 1 wt.% to 5 wt.% and 10 wt.% induces (i) a change in the relative intensity ratio of the Raman lines located at 145 and 1595 cm-1, which are attributed to the Eg(1) vibrational mode of TiO2 and the graphitic structure of SWCNHs; and (ii) a gradual increase in the IR band absorbance at 1735 cm-1 because of the formation of new carboxylic groups on the SWCNHs' surface. The best photocatalytic properties were obtained for the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.%, when approx. 92.4% of AMOX removal was achieved after 90 min of UV irradiation. The TiO2/SWCNH composite is a more efficient catalyst in AMOX photodegradation than TiO2 as a consequence of the SWCNHs' presence, which acts as a capture agent for the photogenerated electrons of TiO2 hindering the electron-hole recombination. The high stability of the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.% is proved by the reusing of the catalyst in six photodegradation cycles of the 98.5 μM AMOX solution, when the efficiency decreases from 92.4% up to 78%.

Analysis of CN emission as a marker of organic compounds in meteoroids using laboratory simulated meteors

Fragments of small solar system bodies entering Earth’s atmosphere have possibly been important contributors of organic compounds to the early Earth. The cyano radical (CN) emission from meteors is considered as potentially one of the most suitable markers of organic compounds in meteoroids, however, its detection in meteor spectra has been thus far unsuccessful. With the aim to improve our abilities to identify CN emission in meteor observations and use its spectral features to characterize the composition of incoming asteroidal meteoroids, we present a detailed analysis of CN emission from high-resolution spectra of 22 laboratory simulated meteors including ordinary, carbonaceous, and enstatite chondrites, as well as a large diversity of achondrites (i.e., ureilite, aubrite, lunar, martian, howardite, eucrite, and diogenite), mesosiderite, and iron meteorites. We describe the variations of CN emission from different classes of asteroidal meteor analogues, its correlation and time evolution relative to other major meteoroid components. We demonstrate that CN can be used as a diagnostic spectral feature of carbonaceous and carbon-rich meteoroids, while most ordinary chondrites show no signs of CN. Our results point out strong correlation between CN and H emission and suggest both volatile features are suitable to trace contents of organic matter and water molecules present within meteoroids. For the application in lower resolution meteor observations, we demonstrate that CN can be best recognized in the early stages of ablation and for carbon-rich materials by measuring relative intensity ratio of CN band peak to the nearby Fe I-4 lines.

Role of La 5p in Bulk and Quantum-Confined Solids Probed by the La 5p54f1 3D1 Excitonic Final State of Resonant Inelastic X-ray Scattering

The varied electronic localization of rare earth elements is essential to functional materials and a key to tailoring their properties. We establish with unprecedented spectral resolution the excitonic nature of the lanthanum 5p54f1 3D1 and 3D2 final states of resonant inelastic X-ray scattering (RIXS) at the La N4,5 edges. We extract the intrinsic lifetime, energy distance, and relative intensity ratio from single crystal LaAlO3 and construct an empirical model. With help of the model, we precisely determine the RIXS 3D1 final state position and identify La 5p as a descriptor of covalency with the host material. For metallic lanthanum, La3+ ions in mixed-covalent-ionic simple oxides and phosphates, and ionic salts alike, we find a sizable chemical shift, indicating band-like and free-ion-like La. The different electronic relaxation of the La 5p5 hole and the La 4f1 electron is discussed with local and nonlocal screening contributions. In addition, the energetics of the excitonic La 5p54f1 Coulomb attraction is quantified in its variation from lanthanum metal to mixed-covalent-ionic La2O3 and the ionic LaF3 salt. The power of the approach and analysis is applied to map the influence of geometric quantum confinement to La 5p sharing within quantum dots and quantum wires in comparison to bulk-like microrods of monoclinic LaPO4.

Synthesis of Graphene-like Materials from Acetylene Black, Activated Carbon, and Ketjenblack via Separated Microwave Electric and Magnetic Field Heating.

Acetylene black, activated carbon, and Ketjenblack were subjected to microwave heating up to 1000 °C under N2 atmosphere to rapidly convert them into graphene-like materials. Few carbon materials exhibit a favorable increase in the intensity of the G' band with increasing temperature. Upon electric field heating of acetylene black to 1000 °C, the observed relative intensity ratios of D and G bands (or G' and G band) were equivalent to those of reduced graphene oxide heated under identical conditions. In addition, microwave irradiation under different conditions, i.e., electric field or magnetic field heating, produced graphene of qualities different from those of the same carbon material conventionally treated at the same temperature. We propose that this difference arises from the different mesoscale temperature gradients. The conversion of inexpensive acetylene black and Ketjenblack into graphene-like materials within 2 min of microwave heating is a major achievement toward low-cost mass synthesis of graphene.

Gas-phase formation of Grignard-type organolanthanide (III) ions RLnCl3 - : The influences of lanthanide center and hydrocarbyl group.

Compared with organomagnesium compounds (Grignard reagents), the Grignard-type organolanthanides (III) exhibit several utilizable differences in reactivity. However, the fundamental understanding of Grignard-type organolanthanides (III) is still in its infancy. Decarboxylation of metal carboxylate ions is an effective method to obtain organometallic ions that are well suited for gas-phase investigation using electrospray ionization (ESI) mass spectrometry in combination with density functional theory (DFT) calculations. The (RCO2 )LnCl3 - (R = CH3 , Ln = La-Lu except Pm; Ln = La, R = CH3 CH2 , CH2 CH, HCC, C6 H5 , and C6 H11 ) precursor ions were produced in the gas phase via ESI of LnCl3 and RCO2 H or RCO2 Na mixtures in methanol. Collision-induced dissociation (CID) was employed to examine whether the Grignard-type organolanthanide (III) ions RLnCl3 - can be obtained via decarboxylation of lanthanide chloride carboxylate ions (RCO2 )LnCl3 - . DFT calculations can be used to determine the influences of lanthanide center and hydrocarbyl group on the formation of RLnCl3 - . When R = CH3 , CID of (CH3 CO2 )LnCl3 - (Ln = La-Lu except Pm) yielded decarboxylation products (CH3 )LnCl3 - and reduction products LnCl3 ·- with a variation in the relative intensity ratio of (CH3 )LnCl3 - /LnCl3 ·- . The trend is as follows: (CH3 )EuCl3 - /EuCl3 ·- < (CH3 )YbCl3 - /YbCl3 ·- ≈ (CH3 )SmCl3 - /SmCl3 ·- < other (CH3 )LnCl3 - /LnCl3 ·- , which complies with the trend of Ln (III)/Ln (II) reduction potentials in general. When Ln = La and hydrocarbyl groups were varied as CH3 CH2 , CH2 CH, HCC, C6 H5 , and C6 H11 , the fragmentation behaviors of these (RCO2 )LaCl3 - precursor ions were diverse. Except for (C6 H11 CO2 )LaCl3 - , the four remaining (RCO2 )LaCl3 - (R = CH3 CH2 , CH2 CH, HCC, and C6 H5 ) ions all underwent decarboxylation to yield RLaCl3 - . (CH2 CH)LaCl3 - and especially (CH3 CH2 )LaCl3 - are prone to undergo β-hydride transfer to form LaHCl3 - , whereas (HCC)LaCl3 - and (C6 H5 )LaCl3 - are not. A minor reduction product, LaCl3 ·- , was formed via C6 H5 radical loss of (C6 H5 )LaCl3 - . The relative intensities of RLaCl3 - compared to (RCO2 )LaCl3 - decrease as follows: HCC > CH2 CH > C6 H5 > CH3 > CH3 CH2 >> C6 H11 (not visible). A series of Grignard-type organolanthanide (III) ions RLnCl3 - (R = CH3 , Ln = La-Lu except Pm; Ln = La, R = CH3 CH2 , CH2 CH, HCC, and C6 H5 ) were produced from (RCO2 )LnCl3 - via CO2 loss, whereas (C6 H11 )LaCl3 - did not. The experimental and theoretical results suggest that the reduction potentials of Ln (III)/Ln (II) couples as well as the bulkiness and hybridization of hydrocarbyl groups play important roles in promoting or limiting the formation of RLnCl3 - via decarboxylation of (RCO2 )LnCl3 - .

A model incorporating histopathology and preoperative gadoxetic acid-enhanced MRI to predict early recurrence of hepatocellular carcinoma without microvascular invasion after curative hepatectomy.

To assess the predictive value of preoperative gadoxetic acid (GA)-enhanced magnetic resonance imaging (MRI) features and postoperative histopathological grading for early recurrence of hepatocellular carcinoma (HCC) without microvascular invasion (MVI) after curative hepatectomy. A total of 85 MVI-negative HCC cases were retrospectively analyzed. Cox analyses were used to identify the independent predictors of early recurrence (within a 24 months span). The clinical prediction Model-1 or Model-2 was established without or with postoperative pathological factor, respectively. Nomogram models were constructed and receiver operating characteristic (ROC) curve analysis was used to assess the models' predictive ability. Internal validation of the prediction models for early HCC recurrence was performed using a bootstrap re-sampling approach. In the multivariate cox regression analysis, Edmondson-Steiner grade, peritumoral hypointensity on hepatobiliary phase (HBP), and relative intensity ratio (RIR) in HBP were identified as independent variables associated with early recurrence. The C-index of the nomogram models and internal validation were both between 0.7 and 0.8, showing good model fitting and calibration effects. The area under the ROC curve (AUC) was 0.781 for Model-1 based on the two preoperative MRI factors. When a third factor, the Edmondson-Steiner grade, was included (Model-2), the AUC increased to 0.834, and the sensitivity increased from 71.4 to 96.4%. Edmondson-Steiner grade, peritumoral hypointensity on HBP, and RIR on HBP can help predict early recurrence of MVI-negative HCC. In comparison with Model-1 (only imaging features), Model-2 (imaging features + histopathological grades) increases the sensitivity in predicting early recurrence of HCC without MVI. Preoperative GA-enhanced MRI signs are of great value in predicting early postoperative recurrence of HCC without MVI, and a combined pathological model was established to evaluate the feasibility and effectiveness of this technique.

X‐ray fluorescence analysis using ultrasonic levitation technique

AbstractA thin film is used as the sample holder for analyzing solutions and solid samples using x‐ray fluorescence (XRF). The incident x‐rays are scattered on the sample and thin film, and the scattered x‐rays serve as background signals in the XRF spectra. To reduce the intensity of the background signal, an ultrasonic levitation method was developed herein for XRF measurements. The ultrasonic levitation device is equipped with a transducer (horn) and reflector, and a small‐size sample is levitated around a node of a generated standing wave; thus, a sample holder is not necessary. Fe solution (2 μL) was analyzed to evaluate the developed instrument. The results obtained using levitation times of 0 and 60 min were compared. The solvent droplet almost evaporated during ultrasonic levitation; therefore, the absorption effects of XRFs and incident x‐rays and the scattering effect of incident x‐rays were reduced. At a levitation time of 60 min, the net intensity of the Fe Kα peak was increased, and the background intensity decreased. The relationship between the levitation time and the net or background intensities of the Fe Kα peak was defined; thus, condensation of the sample droplet was successfully observed. Quantitative analysis was performed using an internal standard method. The relative intensity (ratio of the net intensities of the target and internal standard elements) was proportional to the concentration ratio. Therefore, this method is useful for measuring trace elements at low background intensity and elucidating the process of condensation of a sample droplet.

A novel dual emission ratiometric fluorescence sensor Eu3+/CDs@UiO-66 to achieve Cu2+ detection in water environment

A novel dual-emission ratiometric fluorescent sensor Eu3+/CDs@UiO-66 was synthesized by post-synthesis modifying of UiO-66, a zirconium-based MOF formed by 1,4-phthalic acid (PTA) and Zr4+ , with europium ion (Eu3+) and carbon dots (CDs) and utilized for the determination of Cu2+ ions. The prepared composites not only maintain the excellent optical properties of CDs and Eu3+ but also have good stability in an aqueous solution. At the excitation wavelength of 299 nm, Eu3+/CDs@UiO-66 has two distinct emission peaks at 394 nm and 615 nm, respectively. More interestingly, when the material was dispersed in an aqueous solution containing Cu2+ ions, the characteristic peak of Eu3+ at 615 nm decreased significantly, while the characteristic peak of CDs at 394 nm remained unchanged. In the range of 0–500 μM, the relative fluorescence intensity ratio (F394/F615) linearly increased with increasing Cu2+ ion concentration, and the detection limit was calculated to be 51 nM (3Sb/Ksv). At the same time, the material can also be effectively applied to the detection of Cu2+ in environmental water samples. So Eu3+/CDs@UiO-66 can be developed as a potential ratiometric fluorescent sensor to detect Cu2+ ions.