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Abstract Background With the emergence of photon-counting CT, ultrahigh-resolution (UHR) imaging can be performed without dose penalty. This study aims to directly compare the image quality of UHR and standard resolution (SR) scan mode in femoral artery angiographies. Methods After establishing continuous extracorporeal perfusion in four fresh-frozen cadaveric specimens, photon-counting CT angiographies were performed with a radiation dose of 5 mGy and tube voltage of 120 kV in both SR and UHR mode. Images were reconstructed with dedicated convolution kernels (soft: Body-vascular (Bv)48; sharp: Bv60; ultrasharp: Bv76). Six radiologists evaluated the image quality by means of a pairwise forced-choice comparison tool. Kendall’s concordance coefficient (W) was calculated to quantify interrater agreement. Image quality was further assessed by measuring intraluminal attenuation and image noise as well as by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR). Results UHR yielded lower noise than SR for identical reconstructions with kernels ≥ Bv60 (p

Background: With the emergence of photon-counting CT, ultrahigh-resolution (UHR) imaging can be performed without dose penalty. This study aims to directly compare the image quality of UHR and standard resolution (SR) scan mode in femoral artery angiographies. Methods: After establishing continuous extracorporeal perfusion in four fresh-frozen cadaveric specimens, photon-counting CT angiographies were performed with a radiation dose of 5 mGy and tube voltage of 120 kV in both SR and UHR mode. Images were reconstructed with dedicated convolution kernels (soft: Body-vascular (Bv)48; sharp: Bv60; ultrasharp: Bv76). Six radiologists evaluated the image quality by means of a pairwise forced-choice comparison tool. Kendall's concordance coefficient (W) was calculated to quantify interrater agreement. Image quality was further assessed by measuring intraluminal attenuation and image noise as well as by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR). Results: UHR yielded lower noise than SR for identical reconstructions with kernels ≥ Bv60 (p < 0.001). UHR scans exhibited lower intraluminal attenuation compared to SR (Bv60: 406.4 ± 25.1 versus 418.1 ± 30.1 HU; p < 0.001). Irrespective of scan mode, SNR and CNR decreased while noise increased with sharper kernels but UHR scans were objectively superior to SR nonetheless (Bv60: SNR 25.9 ± 6.4 versus 20.9 ± 5.3; CNR 22.7 ± 5.8 versus 18.4 ± 4.8; p < 0.001). Notably, UHR scans were preferred in subjective assessment when images were reconstructed with the ultrasharp Bv76 kernel, whereas SR was rated superior for Bv60. Interrater agreement was high (W = 0.935). Conclusions: Combinations of UHR scan mode and ultrasharp convolution kernel are able to exploit the full image quality potential in photon-counting CT angiography of the femoral arteries. Relevance statement: The UHR scan mode offers improved image quality and may increase diagnostic accuracy in CT angiography of the peripheral arterial runoff when optimized reconstruction parameters are chosen. Key points: • UHR photon-counting CT improves image quality in combination with ultrasharp convolution kernels. • UHR datasets display lower image noise compared with identically reconstructed standard resolution scans. • Scans in UHR mode show decreased intraluminal attenuation compared with standard resolution imaging. [ABSTRACT FROM AUTHOR]

To characterize the structure and dynamics of metal–-organic frameworks (MOFs) in-depth at the molecular level, it is necessary to pursue high-resolution solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. Spectral resolution is usually affected by the quality of materials and various experimental conditions, of which magic angle (MA) accuracy is a crucial determinant. The current industrial criteria for MA calibration based on the common standard of KBr were found insufficient in guaranteeing optimal resolution MAS NMR for highly ordered MOFs. To drive towards higher-resolution MAS NMR spectroscopy, we propose a calibration protocol for more accurate MA with a higher-precision criterion based on 79Br MAS NMR of KBr, where the linewidth ratio of the fifth-order spinning sideband to the central band of KBr should be less than 1.00. As a result, ultrahigh-resolution 13C cross-polarization (CP) MAS NMR of MOF-5 is achieved with minimal linewidths as low as 4 Hz, and therefore MOF-5 can be used as a new standard convenient for verifying MA accuracy and also optimizing 13C CP conditions. Maintaining high-precision MA under variable temperature (VT) was found challenging on certain commercial MAS NMR probes, as was systematically investigated by VT NMR using KBr and MOF-5. Nevertheless, ultrahigh-resolution MAS NMR spectroscopy with stable MA under VT is employed to reveal fine structures and linker dynamics of a series of Zn-based MOFs with highly regulated structures. The ultrahigh-resolution NMR methodcan be generally applied to study a broad range of MOFs and other materials.

This paper describes a Parallel-Double-Grating Spectrometer (PDGS) with ultrahigh resolution. Two plane reflection gratings are placed in parallel and staggered to form a dispersive component, through which the light passes multiple times, which greatly improves the dispersion capability of the spectrometer, and therefore the resolution. The diffraction characteristics of the dispersive component and the mathematical model of the PDGS are studied. The results of simulation show that using two reflection gratings with a groove density of 168 gr/mm, combined with spectral splicing technology, the PDGS can achieve a measurement waveband from 450 nm to 610 nm with a resolution better than 30.88 pm. Modifying the structural parameters of the PDGS extends the applicability of the optical path structure to spectral bands from ultraviolet to infrared.

In this study, a tunable all-dielectric metalens (TADM) is presented. Focal lengths of incident wavelengths could be tuned by vertically changing the distance between two metalens layers or changing the incident angle of light. By changing the distance between two metalens layers from 5 μm to 32 μm, the tuning ranges of focal lengths are 21.29 μm, 22.77 μm, 22.75 μm, and 22.28 μm for the incident wavelengths of 660 nm, 580 nm, 530 nm, and 480 nm, respectively. The variation in tuning ranges of focal lengths is less than 1 μm. By changing the incident angle of light less than 1°, the tuning ranges of focal lengths are 13.35 μm, 12.87 μm, 15.81 μm, and 17.83 μm for the incident wavelengths of 660 nm, 580 nm, 530 nm, and 480 nm, respectively. The variation in tuning ranges of focal lengths is less than 4.5 μm. TADM exhibits excellent merits in the entire visible spectrum, including the characterizations of achromatism, ultrahigh resolution, and tunability. Such results are very suitable for miniaturized imaging devices, such as lens of smart phones, flexible displays, ultra-lightweight VR/AR glasses, and communication systems with multi-color-channel functionalities. [ABSTRACT FROM AUTHOR]

Flexible anisotropic strain sensors (ASSs) are crucial for comprehending both the magnitudes and directions of complex strains. Some fabrication techniques have been employed to engineer macro-alignments of sensing materials capable of an anisotropic response to strain. However, these sophisticated processes often fail to precisely control the micro-assembly of sensing elements, thereby limiting the sensors' ability in accurately discerning strains below 0.1 %. Here, we propose an ASS based on an aligned magnetic nanowire array (AMNWA). During the fabrication of AMNWAs, an external magnetic field facilitates the alignment of nanowires in a specific direction, while micro fields of nanowires further induce the construction of end-to-end junctions between nanowires, whose conductivity is susceptible to minimum strains. Consequently, the AMNWA demonstrates a remarkable sensitivity to strains parallel to the aligned direction (Gauge factor > 500), allowing the ASS for the discernment of subtle strains as minuscule as 0.0037 % with a theoretical resolution of 0.001 %. The response of the AMNWA presents extreme anisotropy, with negligible sensitivity to strains perpendicular to the aligned direction. By strategically arranging two AMNWAs orthogonally, the magnitude and direction of complex strains can be effectively decoupled. Notably, this configuration enables accurate recognition of strain signals generated by human joint movements. According to these excellent sensing performances, we hold an optimistic outlook on the potential inspiration and reference of AMNWAs for the design and optimization of ASSs. [ABSTRACT FROM AUTHOR]

A hybrid imaging system consisting of a standard computed tomography (CT) scanner and a low-profile photon-counting detector insert in contact with the patient's body has been used to produce ultrahigh-resolution images in a limited volume in chest scans of patients. The detector insert is placed on the patient bed as needed and not attached. Thus, its position and orientation in the scanner is dependent on the patient's position and scan settings. To allow accurate image reconstruction, we devised a method of determining the relative geometry of the detector insert and the CT scanner for each scan using fiducial markers. This method uses an iterative registration algorithm to align the markers in the reconstructed volume from the detector insert to that of the concurrent CT scan. After obtaining precise geometric information of the detector insert relative to the CT scanner, the two complementary sets of images are summed together to create a detailed image with reduced artifacts. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the diagnostic performance of automated deep learning in the detection of coronary artery disease (CAD) on photon-counting coronary CT angiography (PC-CCTA)., Materials and Methods: Consecutive patients with suspected CAD who underwent PC-CCTA between January 2022 and December 2023 were included in this retrospective, single-center study. Non-ultra-high resolution (UHR) PC-CCTA images were analyzed by artificial intelligence using two deep learning models (CorEx, Spimed-AI), and compared to human expert reader assessment using UHR PC-CCTA images. Diagnostic performance for global CAD assessment (at least one significant stenosis ≥ 50 %) was estimated at patient and vessel levels., Results: A total of 140 patients (96 men, 44 women) with a median age of 60 years (first quartile, 51; third quartile, 68) were evaluated. Significant CAD on UHR PC-CCTA was present in 36/140 patients (25.7 %). The sensitivity, specificity, accuracy, positive predictive value), and negative predictive value of deep learning-based CAD were 97.2 %, 81.7 %, 85.7 %, 64.8 %, and 98.9 %, respectively, at the patient level and 96.6 %, 86.7 %, 88.1 %, 53.8 %, and 99.4 %, respectively, at the vessel level. The area under the receiver operating characteristic curve was 0.90 (95 % CI: 0.83-0.94) at the patient level and 0.92 (95 % CI: 0.89-0.94) at the vessel level., Conclusion: Automated deep learning shows remarkable performance for the diagnosis of significant CAD on non-UHR PC-CCTA images. AI pre-reading may be of supportive value to the human reader in daily clinical practice to target and validate coronary artery stenosis using UHR PC-CCTA., Competing Interests: Declaration of competing interest Jean-François Paul is co-founder of Spimed-AI., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

For ultrahigh resolution synthetic aperture radar (SAR), azimuth spectrum aliasing limits the application of frequency-domain autofocus algorithms. Therefore, time-domain autofocus algorithms are often used for ultrahigh resolution SAR imaging. However, the azimuth deramping operation in current time-domain autofocus algorithms may introduce an additional azimuth-dependent phase. This phase can be regarded as a part of the phase error, which significantly reduces the estimation accuracy of the phase error. To address this issue, this article proposes a new time-domain autofocus algorithm based on azimuth scaling transformation (AST) for ultrahigh resolution SAR. In this algorithm, we first adopt the azimuth scaling operation to avoid the azimuth-dependent phase so that the estimation accuracy of error can be greatly improved. Then, for the azimuth-dependent shifts caused by the azimuth scaling operation, we adopt the alignment processing to remove them in azimuth-time domain. Finally, we can estimate the error accurately from the aligned signal. The simulation and measured data were processed to verify the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

For future ultrahigh resolution spaceborne synthetic aperture radar (SAR), it requires the antenna beam capable of large angle scanning in azimuth to increase the azimuth bandwidth and to improve the resolution consequently. To achieve this goal, this paper proposes for the first time a complete implementation scheme based on three-axis attitude maneuvering of satellite platform. Starting from the determination of rotation center, we will deduce the variation of Euler angles during the whole imaging period. Compared with two-dimensional electronical beam-sweeping approach used in phased-array antenna, the most notable advantage of our approach is that it can guarantee azimuth Doppler frequency barely vary along the range line at any azimuth squint angle, which enables the effective decoupling of the signal in azimuth from that in range. Taking advantage of this characteristic, the processing efficiency of high resolution SAR imaging could then be improved to a great extent. Simulation results are presented to verify its effectiveness as well as superiority compared to electronical beam-sweeping.

Stimulated emission depletion (STED) nanoscopy is a promising super‐resolution imaging technique for microstructure imaging; however, the performance of super‐resolution techniques critically depends on the properties of the fluorophores (photostable fluorophores) used. In this study, a suitable probe for improving the resolution of STED nanoscopy was investigated. Quantum dots (QDs) typically exhibit good photobleaching resistance characteristics. In comparison with CdSe@ZnS QDs and CsPbBr3 QDs, Cd‐free InP/ZnSeS QDs have a smaller size and exhibit an improved photobleaching resistance. Through imaging using InP/ZnSeS QDs, we achieved an ultrahigh resolution of 26.1 nm. Furthermore, we achieved a 31 nm resolution in cell experiments involving InP/ZnSeS QDs. These results indicate that Cd‐free InP/ZnSeS QDs have significant potential for application in fluorescent probes for STED nanoscopy. [ABSTRACT FROM AUTHOR]

Signal digitization is a commonly overlooked part of ion mobility-mass spectrometry (IMS-MS) workflows, yet it greatly affects signal-to-noise ratio and MS resolution measurements. Here, we report on the integration of a 2 GS/s, 14-bit ADC with structures for lossless ion manipulations (SLIM-IMS-MS) and compare the performance to a commonly used 8-bit ADC. The 14-bit ADC provided a reduction in the digitized noise by a factor of ~6, owing largely to the use of smaller bit sizes. The low baseline allowed threshold voltage levels to be set very close to the MCP baseline voltage, allowing for as much signal to be acquired as possible without overloading or excessive digitization of MCP baseline noise. Analyses of Agilent tuning mixture ions and a mixture of heavy labeled phosphopeptides showed that the 14-bit ADC provided a ~1.5-2× signal-to-noise (S/N) increase for high intensity ions, such as the Agilent tuning mixture ions and the 2+ and 3+ charge states of many phosphopeptide constituents. However, signal enhancements were as much as 10-fold for low intensity ions, and the 14-bit ADC enabled discernible signal intensities otherwise lost using an 8-bit digitizer. Additionally, the 14-bit ADC required ~14-fold fewer mass spectra to be averaged to produce a mass spectrum with a similar S/N as the 8-bit ADC, demonstrating ~10× higher measurement throughput. The high resolution, low baseline, and fast speed of the new 14-bit ADC enables high performance digitization of MS, IMS-MS, and SLIM-IMS-MS spectra and provides a much better picture of analyte profiles in complex mixtures. [ABSTRACT FROM AUTHOR]

Bedside diagnosis of skin cancer remains a challenging task. The real‐time noninvasive technology of optical coherence tomography (OCT) masters a high diagnostic accuracy in basal cell carcinoma (BCC) but a lower specificity in recognizing imitators and other carcinomas. We investigate the delicate signal of papillary dermis using an in‐house developed ultrahigh resolution OCT (UHR‐OCT) system with shadow compensation and a commercial multi‐focus high resolution OCT (HR‐OCT) system for clinical BCC imaging. We find that the HR‐OCT system struggled to resolve the dark band signal of papillary dermis where the UHR‐OCT located this in all cases and detected changes in signal width. UHR‐OCT is able to monitor extension and position of papillary dermis suggesting a novel feature for delineating superficial BCCs in pursuit of a fast accurate diagnosis. Comprehensive studies involving more patients are imperative in order to corroborate results. [ABSTRACT FROM AUTHOR]

Legacy Fourier transform (FT) mass spectrometers provide robust platforms for bioanalytical mass spectrometry (MS) yet lack the most modern performance capabilities. For many laboratories, the routine investment in next generation instrumentation is cost prohibitive. Field-based upgrades provide a direct path to extend the usable lifespan of MS platforms which may be considered antiquated based on performance specifications at the time of manufacture. Here we demonstrate and evaluate the performance of a hybrid linear ion trap (LTQ)-Orbitrap mass spectrometer that has been enhanced via an external high-performance data acquisition and processing system to provide true absorption mode FT processing during an experimental acquisition. For the application to mass spectrometry imaging, several performance metrics have been improved including mass resolving power, mass accuracy, and dynamic range to provide an FTMS system comparable to current platforms. We also demonstrate, perhaps, the unexpected ability of these legacy platforms to detect usable time-domain signals up to 5 s in duration to achieve a mass resolving power 8× higher than the original platform specification.

Snowflakes are a natural subject for microscopy, but the conditions under which they form, and the minutes-long working time imposed by sublimation, are substantial technical barriers to field microscopy of snow crystals. Building on the work of earlier pioneers, we developed a portable, actively cooled, semi-automated microscope system capable of making z-stacked images of individual snowflakes and small groups of crystal specimens at ultrahigh resolution. Field trials of the system in Alaska and Canada produced encouraging results and also suggested directions for further improvement. [ABSTRACT FROM AUTHOR]

Chromatographic theory has predicted that narrow open tubular (OT) columns are essential toward achieving ultrahigh-efficiency liquid chromatographic separations. It is also well-recognized that low loadability is a major issue for capitalizing the benefits of open tubular liquid chromatography (OTLC). To mitigate this issue, researchers have tried to increase surface area of or create a thick porous coating on the column wall. In this work, we hypothesize that a thin dense non-porous coating is well-suited for us to achieve ultrahigh efficiency or ultrahigh peak capacity if the inner diameter of the OT column is small (e.g., 1−2 µm). We first discuss the rationale of this hypothesis. To provide evidence to further support the hypothesis, we prepare, optimize and characterize the coating for high-resolution separations. We utilize columns prepared under the optimized conditions to separate a peptide sample form E. coli lysate digested first by pepsin and then by trypsin, and we show ultrahigh-peak-capacity results (770 within 47 min using a 45-cm-long column and 2000 within 155 min using a 155-cm-long column). The coating is stable, and the coating method is reproducible. Ultrahigh-resolution separations and ultra-sensitive analyses are critically important and currently challenging for analyses of complex proteomics samples; employing narrow OT columns can alleviate this problem effectively.

We developed a 2‐inch, 2000 ppi shadow mask based on micronthin, free‐standing silicon nitride (SiNx) membrane for patterning OLED displays. Its layer composition and fabrication process were optimized to yield an ultra‐flat, self‐tensioned silicon nitride mask (SNM) that can achieve a submicron shadow distance limited only by the thickness of the membrane in line‐of‐sight vacuum depositions. [ABSTRACT FROM AUTHOR]

This paper provides an overview of publications related to the study of submesoscale ocean variability. The significant progress achieved recently in understanding the special role of submesoscale processes in the formation of ocean circulation and ocean–atmosphere interaction, including modulation of the heat and gas exchange of the two media and their impact on the flux of biogenic elements into the top layer of the ocean, is emphasized. The necessity of conducting a study of submesoscale ocean variability in order to improve the quality of short-term marine forecasts is noted. Marine forecasts of the new level will be based on models with ultrahigh spatial resolution. The models will allow one to describe the reverse cascade of energy in the submesoscale range. In connection with the fact that new instruments capable of conducting 2–10 km surface observations of seas and oceans will be launched in the next five years, the possibilities of using the Black Sea as a testing area for the development of numerical models of circulation in a basin with a resolution of no less than a kilometer and improving methods of analysis and assimilation of observational technologies of the next generation are discussed. [ABSTRACT FROM AUTHOR]

Heavy metal ion pollution is a pressing global concern with detrimental effects on the environment and human health. To address this issue, we have developed an ultrahigh-resolution multicolor sensing platform for the specific detection of silver ions (Ag(I)). The method employs the nanozyme of platinum nanoparticles (PtNPs) as a link to control the etching of gold nanorods (AuNRs). Through specific binding with Ag(I), the PtNPs hinder the catalase-like activity responsible for hydrogen peroxide (H 2 O 2) decomposition. This inhibition enables the Fenton reaction between H 2 O 2 and ferrous ions, generating highly oxidizing hydroxyl free radicals (·OH). The resulting etching of AuNRs induces a blue-shift in their local surface plasmon resonance (LSPR) absorption spectra. The degree of blue-shift is directly proportional to the Ag(I) concentration, facilitating trace-level detection. Furthermore, the aspect ratio change of the AuNRs yields distinguishable colors. In contrast to common multicolor sensors relying on nanozyme horseradish peroxidase (HRP) activity, which exhibits an inverse relationship between AuNR etching and target concentration, our approach demonstrates a proportional response. This unique characteristic enables ultrahigh-resolution multicolor detection of Ag(I) visible to the naked eye. We anticipate that this innovative sensing platform will pave the way for nanosensor development in environmental monitoring and food safety detection. • An ultrahigh-resolution multicolor detector via reverse etching of AuNRs was developed. • The multicolor assay displays a multi-color change for analysis of trace silver ions. • The reverse etching of AuNRs exhibits a proportional response to the silver ion concentration. • The platform was demonstrated with high assay ability and practicability for Ag(I) analysis. [ABSTRACT FROM AUTHOR]

Forepaw somatosensory stimulation induces neural activities in relay thalamic nuclei, the primary somatosensory cortex of forelimb (S1FL), and the secondary somatosensory cortex (S2). However, rodent fMRI studies of somatosensory stimulation have commonly reported BOLD changes only in S1FL, which may be due to side effects of anesthetics and/or the low sensitivity in the thalamus. Thus, we have obtained mouse BOLD fMRI under newly-adopted ketamine-xylazine anesthesia. High-resolution BOLD fMRI obtained with same imaging parameters at 9.4T versus 15.2T shows the improvement of functional detectability by ≥ 2 times at 15.2T due to higher signal intensity and larger BOLD response. The fMRI responses at 15.2T were robustly observed at well-known somatosensory networks including thalamus. Second, echo-time-dependent BOLD signals are dominant based on multi-echo fMRI data. A ratio of BOLD responses in S1FL to thalamus is ∼2, which is not related to different baseline T 2 ∗ or different cerebral blood volume. Third, group-averaged 15.2T BOLD maps show activities in S1FL, S2, motor cortices, and thalamic nuclei, which agree well with neural tracing network data from the Allen Institute, demonstrating that fMRI detects entire somatosensory networks. Our data suggest that ultrahigh field fMRI provides a unique window into understanding functional networks in normal and transgenic mouse models noninvasively. • Higher magnetic field strength increases temporal SNR for high resolution mouse fMRI. • Field strength-dependent tSNR translates into an improvement in functional detectability. • Source of mouse fMRI signals is the linear-TE-dependent BOLD effect at 15.2 T. • Functional response to forepaw stimulation was robustly detected in sensory-related regions including thalamic nuclei. • Somatosensory networks measured by BOLD fMRI is consistent with the neural tracing connectivity map. [ABSTRACT FROM AUTHOR]

Geometrical restraints provide key structural information for the determination of biomolecular structures at lower resolution by experimental methods such as crystallography or cryo‐electron microscopy. In this work, restraint targets for nucleic acids bases are derived from three different sources and compared: small‐molecule crystal structures in the Cambridge Structural Database (CSD), ultrahigh‐resolution structures in the Protein Data Bank (PDB) and quantum‐mechanical (QM) calculations. The best parameters are those based on CSD structures. After over two decades, the standard library of Parkinson et al. [(1996), Acta Cryst. D52, 57–64] is still valid, but improvements are possible with the use of the current CSD database. The CSD‐derived geometry is fully compatible with Watson–Crick base pairs, as comparisons with QM results for isolated and paired bases clearly show that the CSD targets closely correspond to proper base pairing. While the QM results are capable of distinguishing between single and paired bases, their level of accuracy is, on average, nearly two times lower than for the CSD‐derived targets when gauged by root‐mean‐square deviations from ultrahigh‐resolution structures in the PDB. Nevertheless, the accuracy of QM results appears sufficient to provide stereochemical targets for synthetic base pairs where no reliable experimental structural information is available. To enable future tests for this approach, QM calculations are provided for isocytosine, isoguanine and the iCiG base pair. Revised geometrical parameters are proposed for the Watson–Crick pairs of nucleobases, for use as restraints in modeling and refinement of the structures of nucleic acids. Accurate values of these parameters were derived (and compared) from small‐molecule Cambridge Structural Database structures, from super accurate ultrahigh‐resolution nucleic acid structures in the Protein Data Bank, and from quantum mechanical calculations. The effect of base pairing on the molecular geometry of the nucleobases is also investigated. [ABSTRACT FROM AUTHOR]

A heavy crude oil has been treated with deuterated alkylating reagents (CD3I and C2D5I) and directly analyzed without any prior fractionation and chromatographic separation by high-field Orbitrap Fourier Transform Mass Spectrometry (FTMS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) using electrospray ionization (ESI). The reaction of a polycyclic aromatic sulfur heterocycles (PASHs) dibenzothiophene (DBT), in the presence of silver tetrafluoroborate (AgBF4) with ethyl iodide (C2H5I) in anhydrous dichloroethane (DCE) was optimized as a sample reaction to study heavy crude oil mixtures, and the reaction yield was monitored and determined by proton nuclear magnetic resonance spectroscopy (1H-NMR). The obtained conditions were then applied to a mixture of standard aromatic CH-, N-, O- and S-containing compounds and then a heavy crude oil, and only sulfur-containing compounds were selectively alkylated. The deuterium labeled alkylating reagents, iodomethane-d3 (CD3I) and iodoethane-d5 (C2D5I), were employed to the alkylation of heavy crude oil to selectively differentiate the tagged sulfur species from the original crude oil.

We present a new analysis methodology for arbitrary complex molecular systems using ultrahigh-resolution mass spectrometry and isotope exchange. The kinetics of the hydrogen-deuterium exchange reaction is described for large biomacromolecules. The possible applications of the proposed methodology for the analysis of linear oligosaccharides, proteins, and molecular ensemble of humic acids are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT The current study presents AEOLUS-RIO2016, an ultrahigh resolution wind forecasting system that was developed and implemented operationally for supporting the Hellenic Olympic Sailing Team during the sailing events at the Rio de Janeiro 2016 Summer Olympic Games. The forecasting system was built around the state-of-the-art numerical weather prediction Weather Research and Forecasting model, ported to a high performance computing infrastructure that ensured the reliability and timeliness of the provided service. Advanced web mapping tools were employed for communicating forecasts effectively to the athletes and coaches throughout the period of the sailing events. Prior to the operational deployment of AEOLUS-RIO2016, sensitivity experiments were carried out, focusing on the representation of topography and land use and aiming at improving wind forecasts. The results suggest that the employment of very high resolution and up-to-date terrestrial data allowed model performance to be improved, especially in terms of the wind direction guidance provided. Considering the period of the sailing events, the evaluation of AEOLUS-RIO2016 revealed an overall satisfactory performance. Notably, however, it was found that the system failed to provide reliable wind guidance on specific days. A posteriori implementation of the model using an alternative source for providing initial and lateral boundary conditions showed notable improvements in model performance. [ABSTRACT FROM AUTHOR]

Background: The reconnection of left atrial-pulmonary vein (LA-PV) conduction after the initial procedure of pulmonary vein (PV) isolation is not rare, and is one of the main cause of atrial fibrillation (AF) recurrence after PV isolation.Objective: We investigated feasibility of a new ultrahigh-resolution mapping system using a 64-pole small basket catheter for the identification of LA-PV conduction gaps.Methods: This prospective study included 31 consecutive patients (20 with persistent AF) undergoing a second ablation after a PV isolation procedure with LA-PV reconnected conduction at any of the 4 PVs. An LA-PV map was created using the mapping system, and ablation was performed at the estimated gap location.Results: The propagation map identified 54 gaps from 39 ipsilateral PV pairs, requiring manual electrogram reannotation for 23 gaps (43%). Gaps at the anterior and carinal regions of left and right ipsilateral PVs required manual electrogram reannotation more frequently than the other regions. The voltage map could identify the gap only in 19 instances (35%). Electrophysiological properties of the gaps (multiple gaps in the same ipsilateral PVs, conduction time, velocity, width, and length) did not differ between those needing and not needing manual electrogram reannotation. During the gap ablation, either the activation sequence alteration or elimination of PV potentials was observed using a circular catheter placed in the PV, suggesting that all the identified gaps were correct.Conclusion: This new electroanatomic mapping system visualized all the LA-PV gaps in patients undergoing a second AF ablation. [ABSTRACT FROM AUTHOR]

Myelin protein 2 (P2) is a peripheral membrane protein of the vertebrate nervous system myelin sheath, having possible roles in both lipid transport and 3D molecular organization of the multilayered myelin membrane. We extended our earlier crystallographic studies on human P2 and refined its crystal structure at an ultrahigh resolution of 0.72 Å in perdeuterated form and 0.86 Å in hydrogenated form. Characteristic differences in C−H…O hydrogen bond patterns were observed between extended β strands, kinked or ending strands, and helices. Often, side-chain C−H groups engage in hydrogen bonding with backbone carbonyl moieties. The data highlight several amino acid residues with unconventional conformations, including both bent aromatic rings and twisted guanidinium groups on arginine side chains, as well as non-planar peptide bonds. In two locations, such non-ideal conformations cluster, providing proof of local functional strain. Other ultrahigh-resolution protein structures similarly contain chemical groups, which break planarity rules. For example, in Src homology 3 (SH3) domains, a conserved bent aromatic residue is observed near the ligand binding site. Fatty acid binding protein (FABP) 3, belonging to the same family as P2, has several side chains and peptide bonds bent exactly as those in P2. We provide a high-resolution snapshot on non-ideal conformations of amino acid residues under local strain, possibly relevant to biological function. Geometric outliers observed in ultrahigh-resolution protein structures are real and likely relevant for ligand binding and conformational changes. Furthermore, the deuteration of protein and/or solvent are promising variables in protein crystal optimization.

Recently developed ultrahigh resolution optical fiber grating sensors provide powerful tools for crustal deformation monitoring thanks to their unique advantages such as high resolution, low cost, easy deployment, and capability of remote and multiplexed sensing. This paper reviews the development of several types of fiber-optic sensors with ultrahigh resolution in quasi-static domain, including a fiber Bragg grating sensor interrogated with a narrow-linewidth wavelength-sweeping laser, a fiber grating based Fabry–Perot interferometer sensor by using Pound–Drever–Hall technique, sensors interrogated with sideband interrogation method, and the realization of time division multiplexed ultrahigh resolution fiber sensors. The implementation of fiber grating sensors for in situ measurement of crustal deformation are also introduced. [ABSTRACT FROM PUBLISHER]

This paper describes a Parallel-Double-Grating Spectrometer (PDGS) with ultrahigh resolution. Two plane reflection gratings are placed in parallel and staggered to form a dispersive component, through which the light passes multiple times, which greatly improves the dispersion capability of the spectrometer, and therefore the resolution. The diffraction characteristics of the dispersive component and the mathematical model of the PDGS are studied. The results of simulation show that using two reflection gratings with a groove density of 168 gr/mm, combined with spectral splicing technology, the PDGS can achieve a measurement waveband from 450 nm to 610 nm with a resolution better than 30.88 pm. Modifying the structural parameters of the PDGS extends the applicability of the optical path structure to spectral bands from ultraviolet to infrared. [ABSTRACT FROM AUTHOR]

Ultrahigh resolution small animal PET systems require small pixel size scintillators. We developed an ultrahigh resolution small animal PET system using fine LYSO pixels, which were 0.32 mm×0.5 mm×5.0 mm. The LYSO pixels were combined into a 22×15 matrix with a 0.1 mm thick BaSO 4 reflector between them. The LYSO block was 9.24 mm×9.0 mm×5 mm, and it was optically coupled to a 4×4 through silicon via silicon photomultiplier (TSV Si-PM) array that has smaller gaps between channels with a 1-mm thick light guide. We made eight Si-PM-based block detectors and arranged them octagonally to form a PET detector ring. At the center, the spatial resolution of the developed PET system, which was reconstructed by filtered back projection (FBP), was 0.6-mm FWHM. The sensitivity at the axial center was 0.5%. The peak noise equivalent count rate (NECR) was 12.5 k cps. We obtained high resolution images of phantoms and small animals with the developed PET system. With these results, we conclude that a high resolution PET system is possible with 0.32 mm pixel LYSO scintillators. [ABSTRACT FROM AUTHOR]