Combined Scanning Research Articles

Distribution of hydrogen atoms at metallurgical microphases of X52 pipeline steel studied by scanning Kelvin probe force microscopy and finite element modelling

The work combined scanning Kelvin probe force microscopy measurements and finite element modelling to study the diffusion and distribution of hydrogen (H) atoms at metallurgical microphases contained in X52 pipeline steel. Results show that the pearlite contained in the steel is more stable than the ferrite during electropolishing, as indicated by the measured topographic profiles and Volta potentials. The hydrogen (H)-charging enhances the electrochemical activity of both pearlite and ferrite, as shown by increased Volta potential and thus the decreased work function. As the H-charging time increases, the Volta potentials of both phases further increase, implying that their activities increase with the H-charging time. The pearlite has a greater Volta potential and thus a lower work function than the ferrite. This is associated with more H atoms accumulating at the pearlite than at the ferrite. The H atom diffusion and accumulation are affected by H diffusivity at phase boundaries, H-trap binding energy and the number of traps in the steel.

Trueness and precision of combined healing abutment scan body system scans at different sites of maxilla after multiple repositioning of the scan body

ObjectivesTo evaluate the accuracy of the scans of the combined healing abutment-scan body (CHA-SB) system located at different sites of the maxilla when SBs are replaced in between each scan. MethodsThree SBs were seated into HAs located at the central incisor, first premolar, and first molar sites of a maxillary model inside a phantom head, and the model was scanned extraorally (CEREC Primescan SW 5.2). This procedure was repeated with new SBs until a total of 10 scans were performed. Standard tessellation language files of CHA-SBs at each implant location were isolated, transferred into analysis software (Geomagic Control X), and superimposed over the proprietary library files to analyze surface (root mean square), linear, and angular deviations. Trueness and precision were evaluated with one-way analysis of variance and Tukey tests. The correlation between surface and angular deviations was analyzed with Pearson's correlation (α=0.05). ResultsMolar implant scans had the highest surface and angular deviations (P≤.006), while central incisor implant scans had higher precision (surface deviations) than premolar implant scans (P=.041). Premolar implant scans had higher accuracy than central incisor implant scans on the y-axis (P≤.029). Central incisor implant scans had the highest accuracy on the z-axis (P≤.018). A strong positive correlation was observed between surface and angular deviations (r = 0.864, P<.001). ConclusionCentral incisor implant scans mostly had high accuracy and molar implant scans mostly had lower trueness. SBs were mostly positioned apically; however, the effect of SB replacement can be considered small as measured deviations were similar to those in previous studies and the precision of scans was high. Clinical SignificanceRepositioning of scan bodies into healing abutments would be expected to result in similar single crown positioning regardless of the location of the implant, considering high scan precision with the healing abutment-scan body system. The duration of the chairside adjustments of crowns in the posterior maxilla may be longer than those in the anterior region.

Synthesis of a Porous [14]Annulene Graphene Nanoribbon and a Porous [30]Annulene Graphene Nanosheet on Metal Surfaces.

The electrical and mechanical properties of graphene-based materials can be tuned by the introduction of nanopores, which are sensitively related to the size, morphology, density, and location of nanopores. The synthesis of low-dimensional graphene nanostructures containing well-defined nonplanar nanopores has been challenging due to the intrinsic steric hindrance. Herein, we report the selective synthesis of one-dimensional (1D) graphene nanoribbons (GNRs) containing periodic nonplanar [14]annulene pores on Ag(111) and two-dimensional (2D) porous graphene nanosheet containing periodic nonplanar [30]annulene pores on Au(111), starting from a same precursor. The formation of distinct products on the two substrates originates from the different thermodynamics and kinetics of coupling reactions. The reaction mechanisms were confirmed by a series of control experiments, and the appropriate thermodynamic and kinetic parameters for optimizing the reaction pathways were proposed. In addition, the combined scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations revealed the electronic structures of porous graphene structures, demonstrating the impact of nonplanar pores on the π-conjugation of molecules.

Synthesis of a Porous [14]Annulene Graphene Nanoribbon and a Porous [30]Annulene Graphene Nanosheet on Metal Surfaces

AbstractThe electrical and mechanical properties of graphene‐based materials can be tuned by the introduction of nanopores, which are sensitively related to the size, morphology, density, and location of nanopores. The synthesis of low‐dimensional graphene nanostructures containing well‐defined nonplanar nanopores has been challenging due to the intrinsic steric hindrance. Herein, we report the selective synthesis of one‐dimensional (1D) graphene nanoribbons (GNRs) containing periodic nonplanar [14]annulene pores on Ag(111) and two‐dimensional (2D) porous graphene nanosheet containing periodic nonplanar [30]annulene pores on Au(111), starting from a same precursor. The formation of distinct products on the two substrates originates from the different thermodynamics and kinetics of coupling reactions. The reaction mechanisms were confirmed by a series of control experiments, and the appropriate thermodynamic and kinetic parameters for optimizing the reaction pathways were proposed. In addition, the combined scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations revealed the electronic structures of porous graphene structures, demonstrating the impact of nonplanar pores on the π‐conjugation of molecules.

Probing Reaction Heterogeneity in Thick Electrodes: LiFePO4 Versus LiNi0.6Mn0.2Co0.2O2

Introducing thick electrodes is a sound practice for increasing the energy density of lithium-ion batteries by minimizing the ratio of inactive components at device level. However, the inferior rate performance of the thick electrodes, which is believed to be caused by the inhomogeneous reaction, limits their further applications. In this study, we investigate the reaction distribution in LiFePO4 and LiNi0.6Mn0.2Co0.2O2 thick electrodes with combined scanning X-ray fluorescence (XRF) microscopy and X-ray absorption near edge structure (XANES) spectroscopy. 2D XRF-XANES imaging shows discharge reaction is highly non-uniform in the LFP electrode’s depth direction, the degree of which increases with the discharge rate. In contrast, NMC retains a uniform SOC distribution up to 1C (or 1.5C) rate. The XRF-XANES observations are verified by ToF-SIMS measurements. The different reaction distributions observed in LFP and NMC is explained by P2D modeling and has a thermodynamic origin Figure 1

Requirements for dose calculation on an active scanned proton beamline for small, shallow fields

Introduction:A growing interest in using proton pencil beam scanning in combination with collimators for the treatment of small, shallow targets, such as ocular melanoma or pre-clinical research emerged recently. This study aims at demonstrating that the dose of a synchrotron-based PBS system with a dedicated small, shallow field nozzle can be accurately predicted by a commercial treatment planning system (TPS) following appropriate tuning of both, nozzle and TPS. Materials:A removable extension to the clinical nozzle was developed to modify the beam shape passively. Five circular apertures with diameters between 5 to 34mm, mounted 72cm downstream of a range shifter were used. For each collimator treatment plans with spread-out Bragg peaks (SOBP) with a modulation of 3 to 30mm were measured and calculated with GATE/Geant4 and the research TPS RayStation (RS11B-R). The dose grid, multiple coulomb scattering and block discretization resolution were varied to find the optimal balance between accuracy and performance. Results:For SOBPs deeper than 10mm, the dose in the target agreed within 1% between RS11B-R, GATE/Geant4 and measurements for aperture diameters between 8 to 34mm, but deviated up to 5% for smaller apertures. A plastic taper was introduced reducing scatter contributions to the patient (from the pipe) and improving the dose calculation accuracy of the TPS to a 5% level in the entrance region for large apertures. Conclusion:The commercial TPS and GATE/Geant4 can accurately calculate the dose for shallow, small proton fields using a collimator and pencil beam scanning.

Can spectral computed tomography (CT) replace perfusion CT to assess the histological classification of non-small cell lung cancer?

Non-small cell lung cancer (NSCLC) accounts for 80% of total lung cancer cases, it is necessary to distinguish the histological types of NSCLC. This study set out to investigate the correlation between spectral computed tomography (CT) and CT perfusion parameters in patients with NSCLC and to compare the differential diagnostic efficacy of these two imaging modalities for the histological classification of NSCLC. A total of 62 eligible consecutive patients, including 32 with lung adenocarcinoma (LUAD) and 30 with lung squamous cell carcinoma (LUSC), who underwent "one-stop" spectral combined perfusion scan and pathologically confirmed NSCLC at Lanzhou University Second Hospital between September 2020 and December 2021 were prospectively enrolled. The spectral parameters of lesions in the arterial phase (AP) and venous phase (VP) [including iodine concentration (IC), effective atomic number (Zeff), CT40keV, and slope of the spectral curve (K70keV)] and perfusion parameters [blood flow (BF), blood volume (BV), surface permeability (PS), and mean transit time (MTT)] were assessed. Pearson or Spearman correlation analysis was performed to evaluate the correlation between the two imaging parameters, and the DeLong test was used to compare the diagnostic performance of the two imaging modalities. BV and BF were strongly correlated with spectral parameters CT40keV, IC, Zeff, and K70keV in the AP and VP (0.6<r<0.8, P<0.001). MTT was moderately correlated with the above spectral parameters in the AP and VP (0.4<r<0.6, P<0.001). PS was weakly correlated with the above spectral parameters in the VP (0.2<r<0.4, P<0.05). The DeLong test revealed a statistical difference between the area under the curve (AUC) of spectral CT (AUC =0.93, 95% CI: 0.86-0.99, sensitivity =0.94, specificity =0.83) and perfusion CT (AUC =0.81, 95% CI: 0.70-0.92, sensitivity =0.99, specificity =0.57) (P<0.05). Spectral parameters are significantly correlated with perfusion parameters in NSCLC, and spectral CT has a better diagnostic efficacy than perfusion CT in differentiating the histological classification of NSCLC.

Targeted hydrolysis and decrepitation of Mn3AlC precipitates: a route to a novel precursor of rare earth free MnAl–C permanent magnets

In this work, Mn–Al–C alloys consisting of ϵ-MnAl and carbides of the types Mn3AlC and Al4C3 were produced and exposed to water at 80 °C for 35 d. This led to the hydrolysis and decrepitation of the carbides and ultimately, of the material. The hydrolysis behaviour was studied by combined mass spectrometry, thermogravimetry and differential scanning calorimetry. Microstructural studies with scanning electron microscopy and x-ray diffraction were carried out. X-ray computed tomography was used to study the evolution of cracks on a macroscopic scale. As the Mn3AlC precipitates were present as parallel platelets inside the ϵ-grains, the hydrolysis resulted in parallel voids separating regions of ϵ with the same orientation. This ϵ-skeleton could be easily milled into ϵ-flakes, which could be mechanically aligned so that their <001> directions were parallel. The ϵ-powder was transformed into the ferromagnetic τ-phase via heat treatment and is therefore suitable as a novel precursor material for the production of anisotropic τ-MnAl–C-based permanent magnets. Employing such a textured, ϵ-phase, precursor powder in an extrusion process could result in increased texture quality of the τ-phase with correspondingly enhanced magnetic properties.

Evaluation of chemical mechanical planarization slurry dispersion using a combined scanning mobility particle sizer-optical particle sizer system

A combined scanning mobility particle sizer-optical particle sizer (SMPS-OPS) system was evaluated for measuring the dispersion of a chemical mechanical planarization (CMP) slurry. The dilution rate of one particle per droplet was confirmed to minimize agglomeration. The SMPS and OPS measurements showed similar particle size distributions of 400 nm polystyrene latex particles. The particle size distributions of settled ceria and silica slurries were measured using the SMPS-OPS system. The settled commercial ceria slurry showed a decrease in the number concentration in the top layer. In the bottom layer, increases in the concentration of active particles and in the number of large particles were observed. This indicates that large particles were formed during settling of the slurry. In the silica slurry, there was a change in concentration with depth and little change in number of large particles with settling time. The SMPS-OPS system was able to analyze CMP slurries across a wide range of particle diameters for both active and large particles. Therefore, this system can be helpful for analysis of CMP slurry size.

Coronary Computed Tomography Angiography and Abdominal Aortic Calcification Screening among High-Risk Living Kidney Donors

Background: A unique scanning protocol combining coronary computed tomography angiography (CTA) with routine abdominal CTA is being used at the Rabin Medical Center as a method of screening high-risk candidates for living kidney donation. We aim to evaluate the potential impact of coronary CTA on the decision regarding eligibility for kidney donation and its correlation with abdominal aortic calcification (AAC). Methods: CCTA and abdominal CTA results of potential living kidney donors evaluated for donation between September 2020 and November 2021 were retrieved. A retrospective analysis of the abdominal CTA was used to calculate the AAC. Patients’ demographic, clinical, and imaging data were collected from the electronic files, as well as the final decision regarding eligibility for donation. Results: A total of 62 potential kidney donors were evaluated for donation using the combined scan. The mean age was 53.8 years, with male predominance (59.7%). Significant coronary artery stenosis (≥70% luminal stenosis) was present in two patients (3.2%), whereas five patients (8%) had moderate stenosis (50–69%). Thirteen patients (21%) were disqualified from donation due to moderate-to-significant coronary artery disease or abdominal atherosclerosis. The correlation between the coronary artery calcium score and the AAC was found to be positive, with a Pearson correlation coefficient of 0.88 (p &lt; 0.001). Conclusions: The use of coronary CTA in the evaluation of potential kidney donors may has a potential impact on the decision regarding eligibility for donation. A high correlation between the coronary artery calcium score and the AAC was found.

Effects of a focused training on first-year osteopathic medical students' ability to incorporate point-of-care ultrasound in assessment of the anterior knee.

Patients frequently present to the outpatient clinic, urgent care, or emergency department with a painful, swollen knee. Differentiating the underlying etiology can be a challenge for both medical students and seasoned clinicians alike. Because this scenario can represent a time-sensitive emergency, developing skills to diagnose the underlying cause quickly and accurately is essential for proper management, whether the patient would benefit from osteopathic manipulation, prompt administration of antibiotics, or a more invasive procedure like joint aspiration or surgery. The objectives are to determine the effects of a focused ultrasound training on first-year osteopathic medical students' ability to identify normal sonographic anatomy of the anterior knee and to differentiate between three common pathologies: joint effusion, prepatellar bursitis, and cellulitis. First-year osteopathic medical students voluntarily participated in this cross-sectional study. The study protocol included a focused ultrasound training (online materials, brief didactic and single hands-on sessions) followed by a hands-on assessment. A written test and 5-point Likert scale questionnaire were administered before and after the focused training. Nine weeks later, students completed a follow-up written test. The proportion of students who correctly identified common pathologies on written tests before (pretest) and after (posttest) training and on the follow-up written test were compared utilizing the Fisher's exact test. A t test was utilized to compare data from the pretraining and posttraining questionnaires. Of 101 students completing the written pretest andpretraining questionnaire, 95 (94.1 %) completed the written posttest and posttraining questionnaire, and 84 (83.2 %) completed the follow-up written test. Students had limited previous experience with ultrasound; 90 (89.1 %) students had performed six or fewer ultrasound examinations before the focused ultrasound training. On written tests, students accurately identified joint effusion (22.8 % [23/101] pretest, 65.3 % [62/95] posttest, 33.3 % [28/84] follow-up test), prepatellar bursitis (14.9 % [15/101] pretest, 46.3 % [44/95] posttest, 36.9 % [31/84] follow-up test), and cellulitis (38.6 % [39/101] pretest, 90.5 % [86/95] posttest, 73.8 % [62/84] follow-up test). Differences were found between pretest andposttest for identification of all three pathologies (allp<0.001) and between the pretest and 9-week follow-up test for identification of prepatellar bursitis andcellulitis (both p≤0.001). For questionnaires, (where 1=strongly agree, 5=strongly disagree), the mean (standard deviation [SD]) confidence for correctly identifying normal sonographic anatomy of the anterior knee was 3.50 (1.01) at pretraining and 1.59 (0.72) at posttraining. Student confidence in the ability to differentiate joint effusion, prepatellar bursitis, and cellulitis utilizing ultrasound increased from 4.33 (0.78) at pretraining to 1.99 (0.78) at posttraining. For the hands-on assessment, 78.3 % (595 correct/760 aggregated responses) of the time students correctly identified specific sonographic landmarks of the anterior knee. When the evaluation combined real-time scanning with a prerecorded sonographic video clip of the anterior knee, 71.4 % (20/28) accurately identified joint effusion, 60.9 % (14/23) correctly diagnosed prepatellar bursitis, 93.3 % (28/30) recognized cellulitis, and 47.1 % (8/17) diagnosed the normal knee. Our focused training was effective at immediately increasing basic knowledge, as well as confidence of first-year osteopathic medical students when assessing the anterior knee with point-of-care ultrasound. However, spaced repetition and deliberate practice may be useful for learning retention.

Ti-Doping in Silica-Supported PtZn Propane Dehydrogenation Catalysts: From Improved Stability to the Nature of the Pt-Ti Interaction.

Propane dehydrogenation is an important industrial reaction to access propene, the world's second most used polymer precursor. Catalysts for this transformation are required to be long living at high temperature and robust toward harsh oxidative regeneration conditions. In this work, combining surface organometallic chemistry and thermolytic molecular precursor approach, we prepared well-defined silica-supported Pt and alloyed PtZn materials to investigate the effect of Ti-doping on catalytic performances. Chemisorption experiments and density functional calculations reveal a significant change in the electronic structure of the nanoparticles (NPs) due to the Ti-doping. Evaluation of the resulting materials PtZn/SiO2 and PtZnTi/SiO2 during long deactivation phases reveal a stabilizing effect of Ti in PtZnTi/SiO2 with a kd of 0.015 h-1 compared to PtZn/SiO2 with a kd of 0.022 h-1 over 108 h on stream. Such a stabilizing effect is also present during a second deactivation phase after applying a regeneration protocol to the materials under O2 and H2 at high temperatures. A combined scanning transmission electron microscopy, in situ X-ray absorption spectroscopy, electron paramagnetic resonance, and density functional theory study reveals that this effect is related to a sintering prevention of the alloyed PtZn NPs in PtZnTi/SiO2 due to a strong interaction of the NPs with Ti sites. However, in contrast to classical strong metal-support interaction, we show that the coverage of the Pt NPs with TiOx species is not needed to explain the changes in adsorption and reactivity properties. Indeed, the interaction of the Pt NPs with TiIII sites is enough to decrease CO adsorption and to induce a red-shift of the CO band because of electron transfer from the TiIII sites to Pt0.

The applied value in brain gray matter nuclei of patients with early-stage Parkinson’s disease : a study based on multiple magnetic resonance imaging techniques

PurposeThis study compares the observation efficiency of brain gray matter nuclei of patients with early-stage Parkinson’s disease among various Magnetic Resonance Imaging techniques, which include susceptibility weighted imaging (SWI), quantitative susceptibility imaging (QSM), diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI). Based on the findings, this study suggests an efficient combination of scanning techniques for brain gray matter nuclei observation, aiming to provide an opportunity to advance the understanding of clinical diagnosis of early-stage Parkinson’s disease.MethodsForty examinees, including twenty patients who were clinically diagnosed with early Parkinson’s disease with a course of 0.5-6 years (PD group) and twenty healthy controls (HC group), underwent head MRI examination. Philips 3.0T (tesla) MR machine was used to measure the imaging indexes of gray matter nuclei in patients with early Parkinson’s disease. SWI, QSM, DTI and DKI were used for diagnosis. SPSS (Statistical Product and Service Solutions) 21.0 was used for data analysis.ResultsWhen SWI was used, fifteen PD patients and six healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of nigrosome-1 on imaging were 75.0%, 30.0%, 51.7%, 54.5% and 52.5% respectively. By contrast, when QSM was used, 19 PD patients and 11 healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of Nigrosome-one on imaging were 95.0%, 55.0%, 67.9%, 91.7% and 75.0% respectively. The mean kurtosis (MK) value within both the substantia nigra and thalamus, together with the mean diffusivity (MD) within both the substantia nigra and the head of caudate nucleus in PD group was greater than that of HC group. The susceptibility values within the substantia nigra, red nucleus, head of caudate nucleus and putamen of PD group was greater than that of HC group. The MD value in substantia nigra reveals the optimal diagnostic efficiency to distinguish the HC group and the PD group, followed by the MK value in substantia nigra. Specifically, the maximum area under ROC curve (AUC) of the MD value was 0.823, the sensitivity 70.0%, the specificity 85.0%, and the diagnostic threshold 0.414. The area under ROC curve (AUC) of the MK value was 0.695, the sensitivity 95.0%, the specificity 50.0%, and the diagnostic threshold was 0.667. Both of them were statistically significant.ConclusionsIn the early diagnosis of Parkinson’s disease, QSM is more efficient than SWI in observing nigrosome-1 in substantia nigra. In the early diagnosis of Parkinson’s disease, MD and MK values of substantia nigra in DKI parameters have higher diagnostic efficiency. The combined scanning of DKI and QSM has the highest diagnostic efficiency and provides imaging basis for clinical diagnosis of early Parkinson’s disease.

Single-molecule photoelectron tunnelling spectroscopy.

Experimental mapping of transmission is essential for understanding and controlling charge transport through molecular devices and materials. Here we developed a single-molecule photoelectron tunnelling spectroscopy approach for mapping transmission beyond the HOMO-LUMO gap of the single diketopyrrolopyrrole molecule junction using an ultrafast-laser combined scanning tunnelling microscope-based break junction set-up at room temperature. Two resonant transport channels of ultrafast photocurrent are found by our photoelectron tunnelling spectroscopy, ranging from 1.31 eV to 1.77 eV, consistent with the LUMO + 1 and LUMO + 2 in the transmission spectrum obtained by density functional theory calculations. Moreover, we observed the modulation of resonant peaks by varying bias voltages, which demonstrates the ability to quantitatively characterize the effect of the electric field on frontier molecular orbitals. Our single-molecule photoelectron tunnelling spectroscopy offers an avenue that allows us to explore the nature of energy-dependent charge transport through single-molecule junctions.

Nanoscale imaging of quantum dot dimers using time-resolved super-resolution microscopy combined with scanning electron microscopy

Time-resolved super-resolution microscopy was used in conjunction with scanning electron microscopy to image individual colloidal CdSe/CdS semiconductor quantum dots (QD) and QD dimers. The photoluminescence (PL) lifetimes, intensities, and structural parameters were acquired with nanometer scale spatial resolution and sub-nanosecond time resolution. The combination of these two techniques was more powerful than either alone, enabling us to resolve the PL properties of individual QDs within QD dimers as they blinked on and off, measure interparticle distances, and identify QDs that may be participating in energy transfer. The localization precision of our optical imaging technique was ∼3 nm, low enough that the emission from individual QDs within the dimers could be spatially resolved. While the majority of QDs within dimers acted as independent emitters, at least one pair of QDs in our study exhibited lifetime and intensity behaviors consistent with resonance energy transfer from a shorter lifetime and lower intensity donor QD to a longer lifetime and higher intensity acceptor QD. For this case, we demonstrate how the combined super-resolution optical imaging and scanning electron microscopy data can be used to characterize the energy transfer rate.

On the faulting and twinning mediated strengthening and plasticity in a γʹ strengthened CoNi-based superalloy at room temperature

Microscopic defects and their mutual interactions are fundamentally important in deciding the load carrying capacity of structural materials. In this context, the present work reports an unprecedented precipitate shearing mechanism in CoNi-based superalloys at room temperature where L12 ordered γʹ precipitates are embedded within a disordered CoCrNi-rich matrix. A combined electron channelling contrast imaging (ECCI) and scanning transmission electron microscopy (STEM) analysis revealed stacking fault (SF) and SF coupled nano-twin formation that rendered a significant work hardening rate. The observed twinning induced plasticity (TWIP) effect correlates with an excellent combination of yield strength, ultimate tensile strength (UTS) and plasticity of 910 ± 30 MPa, 1360 ± 40 MPa and ∼ 18.5 (%), respectively, as exhibited by the peak aged Co-30Ni-12Cr-7Al-4Ti-2Nb-0.006B alloy at room temperature. Rigorous center of symmetry (COS) analysis on atomic resolution STEM images from the deformed samples unambiguously establishes precipitate shearing via single a/6⟨112⟩{111} partial dislocations resulting in twin formation, succeeding the intrinsic stacking fault (ISF) and complex stacking fault (CSF) of γ and γʹ, respectively. Through thermodynamic and first principles density functional theory calculations, it is demonstrated that the experimentally observed deformation mechanism is directly correlated with the negative stacking fault energy of γ matrix and low CSF energy of the γʹ precipitates. Based on these new findings, the present work demonstrates the flexibility of tuning the composition of CoCrNi containing superalloys to widen the alloy spectrum for designing alloys with improved properties.

Validation of a shortened MR imaging protocol for pediatric spinal pathology.

Conventional pediatric spine MRI protocols have multiple sequences resulting in long acquisition times. Sedation is consequently required. This study evaluates the diagnostic capability of a limited MRI spine protocol for selected common pediatric indications. Spine MRIs at CHEO between 2017 and 2020 were reviewed across pediatric patients younger than four years old. Two blinded neuroradiologists reviewed limited scan sequences, and results were independently compared to previously reported findings from the complete imaging series. T2 sagittal sequences from the craniocervical junction to sacrum and T1 axial sequence of the lumbar spine constitute the short protocol, with the outcomes of interest being cerebellar ectopia, syrinx, level of conus, filum < 2mm, fatty filum, and spinal dysraphism. A total of 105 studies were evaluated in 54 male and 51 female patients (mean age 19.2months). The average combined scan time of the limited sequences was 15min compared to 35min for conventional protocols (delta = 20min). The average percent agreement between full and limited sequences was > 95% in all but identifying a filum < 2mm, where the percent agreement was 87%. Using limited MR sequences had high sensitivity (> 0.91) and specificity (> 0.99) for the detection of cerebellar ectopia, syrinx, fatty filum, and spinal dysraphism. This study demonstrates that selected spinal imaging sequences allow for consistent and accurate diagnosis of specific clinical conditions. A limited spine imaging protocol has potential as a screening test to reduce the need for full-sequence MRI scans. Further work is needed to determine utility of selected imaging for other clinical indications.

Molecular Bridge Engineering for Tuning Quantum Electronic Transport and Anisotropy in Nanoporous Graphene

Recent advances on surface-assisted synthesis have demonstrated that arrays of nanometer wide graphene nanoribbons can be laterally coupled with atomic precision to give rise to a highly anisotropic nanoporous graphene structure. Electronically, this graphene nanoarchitecture can be conceived as a set of weakly coupled semiconducting 1D nanochannels with electron propagation characterized by substantial interchannel quantum interferences. Here, we report the synthesis of a new nanoporous graphene structure where the interribbon electronic coupling can be controlled by the different degrees of freedom provided by phenylene bridges that couple the conducting channels. This versatility arises from the multiplicity of phenylene cross-coupling configurations, which provides a robust chemical knob, and from the interphenyl twist angle that acts as a fine-tunable knob. The twist angle is significantly altered by the interaction with the substrate, as confirmed by a combined bond-resolved scanning tunneling microscopy (STM) and ab initio analysis, and should accordingly be addressable by other external stimuli. Electron propagation simulations demonstrate the capability of either switching on/off or modulating the interribbon coupling by the corresponding use of the chemical or the conformational knob. Molecular bridges therefore emerge as efficient tools to engineer quantum transport and anisotropy in carbon-based 2D nanoarchitectures.

Low-temperature one-step solid state chemical synthesis of GaN nanosheets for conquering polysulfides in Li–S battery

Gallium nitride (GaN) nanosheets have been prepared as an active material for conquering polysulfides in Lithium–Sulfur (Li–S) batteries via one simple synthetic route at 550 °C. The process was carried out in a stainless steel autoclave by using gallium nitrate hydrate, sodium amide and metallic lithium as starting materials. The product was proven to be hexagonal GaN nanosheets by combined X-ray powder diffraction (XRD) pattern and Scanning electron microscopy (SEM). The GaN nanosheets were then used to coat on the Li–S battery separator, and the result proves an effective inhibition of the shutting problem and gives excellent electrochemical properties compared with traditional separators or GaN additives. The battery assembled by GaN coated separator shows good cycling stability with 408 mAh/g and a low capacity fading of 0.6‰ per cycle from 11th to 480th cycle at 2 C due to high utilization of the sulfur-based active species.

Lung Cancer Detection using Fusion, CNN and YOLO in MATLAB

Abstract: Lung Cancer is one of the major causes of deaths in India. Various data analytics and classification approaches have been used to diagnose and find lung cancer in numerous cases. Lung Cancer can only be cured by early tumour diagnosis because the basis of the diseases is yet unknown, making prevention impossible. In order to classify the existence of lung cancer/tumour in a CT picture and PET image, a lung cancer detection method using image processing and deep learning is applied. Using Fusion technique, we first obtain CT scans, then PET images of the same patient, then combine both images into one. The classification carried out using image feature extraction. As a result, the combined CT and PET scan images of the patient are classified as normal or abnormal. The tumour component of the abnormal photos is the focus of the detecting process. Using YOLO and CNN, an effective strategy to identify lung cancer and its phases is one that also seeks to produce more precise results.