CO Recombination Research Articles

Hydrothermal synthesis of Fe3O4@rGO@CdS/Bi2S3 nanocomposite as an efficient, recyclable magnetic photocatalyst for photo-Fenton dye degradation and chromium VI reduction under sunlight

The use of nanocomposites for photocatalytic activities is frequently limited because the suspended catalyst particles are lost during the photocatalytic reaction, and hence, it is difficult to separate them from the reaction mixture. The combination of a magnetic core with nanocomposites could solve these challenges. Hence, in the present work, we synthesized a magnetically separatable Fe3O4@rGO@CdS/Bi2S3 photocatalyst using a simple, efficient, one-step hydrothermal method. A CdS/Bi2S3 binary nanocomposite anchored to the surface of Fe3O4 magnetic nanoparticles wrapped in reduced graphene oxide (rGO), where rGO served as an efficient protective layer for the CdS/Bi2S3 and Fe3O4 nanoparticles. The results showed that Fe3O4@rGO@CdS/Bi2S3 photocatalyst had greater stability and efficient potential for the methylene blue (MB) degradation by photo-Fenton reaction and photoreduction of hexavalent chromium Cr(VI) under natural sunlight. The prepared photocatalyst efficiently degrades 99 % of methylene blue in 70 min at neutral pH, and quick photoreduction of Cr(VI) of 98 % takes place within 40 min. After five cycles, the repeatability of the photocatalytic activity exhibited just a slight reduction in catalytic efficiency.

Developing Tailor-Made Core-Shell Hard Carbon Materials As Anode Materials in Sodium Ion Batteries

The current strong interest in electromotive mobility and the need to transition to an energy grid with sustainable storage devices has led to a renewed interest in sodium ion batteries (SIBs). Hard carbons (HCs) are promising candidates for high-capacity negative electrode materials in SIBs. Their high capacities, however, are often accompanied with high irreversible capacity losses during the initial cycles.[1]Generally, large losses can be connected to irreversible reactions, e.g., the formation of the solid electrolyte interphase (SEI), during the initial sodiation of the HC-material. However, high irreversible capacity values are often in contradiction to the experimentally determined low surface area of the sample material.[1] A better understanding of the structure-property relationship should enable quantification and understanding of the potential of hard carbon materials for SIBs. Hence, the aim is to use analytical techniques to establish a correlation between the structure and the electrochemical characteristics of HC-materials. This has previously been difficult, in part because the sodium storage mechanism is not stoichiometric and due to the disordered structure of HCs.In order to tackle the aforementioned challenges, our approach is to explore whether a core-shell structure can separate sodium storage and solid electrolyte interphase formation. Thus, storage capacity and irreversible losses could be investigated and finally optimized separately. The synthesis of a selection of porous carbon structures serving as the core material, will be attempted. Simultaneously, sodium-conducting shell structures will be developed to allow for separation of sodium ions and electrolyte molecules. Subsequently, the combination of core and shell materials will be undertaken. These anodes should enable high capacities accompanied with low irreversible losses due to optimized SEI-formation.Literature:[1] Matsukawa, Y.; Linsenmann, F.; Plass, M. A.; Hasegawa, G.; Hayashi, K.; Fellinger, T.-P. Beilstein J. Nanotechnol. 2020, 11, 1217–1229.

Molecular Engineering of Rylene Diimides via Sila-Annulation Toward High-Mobility Organic Semiconductors.

The continuous innovation of captivating new organic semiconducting materials remains pivotal in the development of high-performance organic electronic devices. Herein, a molecular engineering by combining sila-annulation with the vertical extension of rylene diimides (RDIs) toward high-mobility organic semiconductors is presented. The unilateral and bilateral sila-annulated quaterrylene diimides (Si-QDI and 2Si-QDI) are designed and synthesized. In particular, the symmetrical bilateral 2Si-QDI exhibits a compact, 1D slipped π-π stacking arrangement through the synergistic combination of a sizable π-conjugated core and intercalating alkyl chains. Combining the appreciable elevated HOMO levels and reduced energy gaps, the single-crystalline organic field-effect transistors (SC-OFETs) based on 2Si-QDI demonstrate exceptional ambipolar transport characteristics with an impressive hole mobility of 3.0 cm2 V-1 s-1 and an electron mobility of 0.03 cm2 V-1 s-1, representing the best ampibolar SC-OFETs based on RDIs. Detailed theoretical calculations rationalize that the larger transfer integral along the π-π stacking direction is responsible for the achievement of the superior charge transport. This study showcases the remarkable potential of sila-annulation in optimizing carrier transport performances of polycyclic aromatic hydrocarbons (PAHs).

Low-cost prototyping of nitinol wires/frames using polymeric cores and sacrificial fixtures with application in individualized frames anchoring through the atrial septum

Self-expanding frames for minimally invasive implants are typically made from nitinol wires and are heat treated to maintain the desired shapes. In the process of heat treatment, nitinol structures are placed in a high-temperature oven, while they are confined by a fixture. During this process, nitinol exerts a high amount of force. Accordingly, a fixture requires high mechanical strength and temperature resistance; this is why fixtures are typically made from metals. The use of metal fixture also increases the turnaround time and cost. However, accelerating this process is beneficial in many applications, such as rapid development of medical implants that are patient-specific. Inspired by the use of sacrificial layers in microfabrication technology, here we propose a novel method for shape setting nitinol wires using a sacrificial metal fixture. In this process, the nitinol wires are first aligned inside copper hypotubes. Next, the forming process is done using hand-held tools to shape complex geometrical structures, annealing the nitinol reinforced by copper, and then selectively etching copper hypotubes in ammonium persulfate solutions. In this process, other sacrificial cores, which are 3D printed or cast from low-cost polymers, are also used. This combination of polymeric cores and minimal use of metals enables reducing the cost and the turnaround time. As a proof of concept, we showed that this process was capable of fabricating springs with mm or sub-mm diameters. The result showed a change of less than 5% in the intended diameter of the nitinol spring with diameters ranging from ~ 0.7 to 1.9 mm, which confirms copper as a suitable sacrificial fixture to obtain the desired complex geometry for nitinol. A metric, based on the elastic strain stored in copper is suggested to predict the possible variation of the intended dimensions in this process. Finally, to demonstrate the potential of this method, as proof of concept, we fabricated NiTi wire frames designed for anchoring through the atrial septum. These frames demonstrated septal defect occluders that were designed based on a patient’s cardiac image available in the public domain. This low-cost rapid fabrication technique is highly beneficial for a variety of applications in engineering and medicine with specific applications in rapid prototyping of medical implants.

Numerical Prediction of Changes in Atmospheric Chemical Compositions During a Solar Energetic Particle Event on Mars

AbstractPrecipitation of solar energetic particles (SEPs) into planetary atmospheres causes changes in atmospheric chemical composition through ionization, dissociation, and excitation of atmospheric molecules. In contrast to the terrestrial atmosphere, where depletion of ozone in the polar mesosphere has been studied by observations and models for decades, there have been no studies on the effects of SEPs on the neutral chemical composition of Mars' present‐day atmosphere. This study provided the first estimate of the impacts of SEPs on neutral chemical composition in the present‐day Martian atmosphere coupling a Monte Carlo model and a one‐dimensional photochemical model. Our results showed that ozone density in the Martian atmosphere might decrease in the altitude range of 20–60 km with a factor 10 maximum enhancement occurring at 40 km during a Halloween‐class SEP event due to an enhanced concentration of HOx. The depletion of ozone occurred in the altitude range of 20–60 km, corresponding to the penetration of protons with an energy range of 4.6–46 MeV. Such ozone depletion should be detected by Trace Gas Orbiter/Nadir and Occultation for MArs Discovery during intense SEP event. A 75% depletion of the ozone density at 40 km can be expected during SEP events occurring once in every 1 year. Therefore, ozone concentration in the Martian atmosphere might sufficiently decrease during a SEP event as on Earth, but through different chemical pathways driven by CO2 ionization and CO recombination catalytic cycle.

Core-shell design for nanocellulosic aerogels by bioinspired spider web-like structure

Inspired by the ultra-lightweight and strong cross-linked spider web, a core–shell design is proposed for fabricating isotropic polymethylsilsesquioxane (PMSQ) rigid-reinforced nanofibers (polypyrrole-coated bacterial cellulose (PPy@BC) and bacterial cellulose (BC)) aerogels via non-directional freeze-drying. As-developed aerogels (PMPBB aerogels) exhibit isotropic properties of compressibility and recoverability, hydrophobicity, low thermal conductivity, and electric conductivity. Benefiting from above characteristics, PMPBB aerogels possess remarkable capacities of oil/organic solvent–water separation, self-cleaning, thermal insulation, and real-time monitoring of human motion signals. The combination of core–shell design with non-directional freeze-drying method offers a valuable reference for seeking innovative methods to develop other advanced aerogels.

Dithienoazepine‐Based Near‐Infrared Dyes: Janus‐Faced Effects of a Thiophene‐Fused Structure on Antiaromatic Azepines

AbstractWe here disclose that the incorporation of thiophene rings into a seven‐membered 8π azepine in a fused fashion produces a useful antiaromatic core for near‐infrared (NIR) dyes. In contrast to dibenzazepine derivatives with bent structures, dithieno‐fused derivatives with electron‐accepting groups adopt flat conformations in the ground state. The dithieno‐fused derivatives exhibited broad absorption spectra that cover the visible region as well as sharp emission bands in the NIR region, which are considerably red‐shifted relative to those of the dibenzo‐fused congeners. Theoretical study revealed two contradictory effects of the less‐aromatic thiophene‐fused structure, i.e., the enhancement of the antiaromaticity of the adjacent azepine ring and the relief of the antiaromaticity through the contribution of a quinoidal resonance form. The combination of the dithienoazepine core with cationic electron‐accepting groups produced a NIR fluorescent dye with an emission at 878 nm in solution.

Dithienoazepine-Based Near-Infrared Dyes: Janus-Faced Effects of a Thiophene-Fused Structure on Antiaromatic Azepines.

We here disclose that the incorporation of thiophene rings into a seven-membered 8π azepine in a fused fashion produces a useful antiaromatic core for near-infrared (NIR) dyes. In contrast to dibenzazepine derivatives with bent structures, dithieno-fused derivatives with electron-accepting groups adopt flat conformations in the ground state. The dithieno-fused derivatives exhibited broad absorption spectra that cover the visible region as well as sharp emission bands in the NIR region, which are considerably red-shifted relative to those of the dibenzo-fused congeners. Theoretical study revealed two contradictory effects of the less-aromatic thiophene-fused structure, i.e., the enhancement of the antiaromaticity of the adjacent azepine ring and the relief of the antiaromaticity through the contribution of a quinoidal resonance form. The combination of the dithienoazepine core with cationic electron-accepting groups produced a NIR fluorescent dye with an emission at 878 nm in solution.

Potential energy curves of molecular nitrogen up to N

The potential energy curves for molecular ions up to N are calculated in an ab initio manner using the multi configurational self-consistent field method. Specifically, we implement in an automatic way a previously used double loop optimisation scheme within the multi configurational self-consisted field method. We obtain the potential energy curves up to N ions with any combination of core, inner valence, and outer valence holes. Finally, we provide the code used to generate these potential energy curves.

Effects of Acid Leaching Post-Treatment Process on the Structural Stability of Pt-Based Intermetallic Catalysts for Fuel Cell Applications

Accelerating the commercialization of polymer electrolyte membrane fuel cells (PEMFCs) requires urgent improvement of a catalyst for oxygen reduction reaction (ORR) that uses expensive precious metals. It is also important to consider the durability of the catalyst, which can affect its performance even after long-term use.In this study, we synthesized a platinum-cobalt (Pt-Co) catalyst with a platinum (Pt) shell and an intermetallic inner core through the acid-leaching post-treatment process. By introducing a transition metal, we greatly improved the ORR activity, while controlling the intermetallic and core-shell structure greatly improved the catalyst's structural stability and durability. We confirmed through X-ray diffraction (XRD) that the Pt-Co compound was aligned in an intermetallic structure, and that the structure was maintained even after the acid leaching post-treatment. In the half-cell test, L10-PtCo@Pt/C, exposed to 0.5 M sulfuric acid solution for 6 hours, exhibited a 3.9-fold increase in mass activity and a 3.3-fold increase in specific activity compared to commercial Pt/C. Additionally, the electrochemical active surface area (ECSA) of L10-PtCo@Pt/C remained stable even after 30,000 cycles, with an insignificant change of 8% or less, while commercial Pt/C decreased by 30% or more. Nevertheless, when acid treatment was applied for longer than this condition, the increase in performance and its retention were significantly reduced. This is due to the fact that with longer acid leaching times, the Pt shell of the catalyst becomes thicker, resulting in a limitation of the alloying effect of the internal intermetallic core.Our study proposes an optimal combination of Pt-Co intermetallic core and Pt shell through precise control of acid leaching post-treatment process. Pt-Co catalysts with well-aligned intermetallic core and the moderate thickness of Pt shell structure can offer a promising solution for improving the performance and durability of PEMFCs, thereby paving the way for their widespread commercialization.

Development of highly stable phytosterol oleogel particle-based emulsions with improved bioaccessibility of ꞵ-carotene

Oral administration is the most preferred route for drug and bioactive delivery, although it raises great challenges due to the involvement of the gastrointestinal (GI) system and limited bioavailability. In this research, gelled oil particle-based emulsion with long shelf life and high gastrointestinal stability was successfully formulated using ꞵ-sitosterol and γ-oryzanol (SO) mixtures, as structuring agents, and tween 80 (TN80) as a surfactant. The effect of TN80 concentration, emulsification speed, γ-oryzanol and ꞵ-sitosterol ratio, and SO concentration was examined. The results show that the particle size was significantly reduced with homogenization speed, surfactant concentration, and SO concentration. The effect of SO concentration was further analyzed under simulated GI conditions and changes in their particle size, zeta potential, morphology, and ꞵ-carotene release were assessed. GI digestion tests revealed that unstructured oil particle-based emulsions exhibit a higher probability for particle coalescence compared to oleogel particle-based emulsions. The extent of lipid digestion was correlated to the particle size, with higher digestion extent at smaller particle size, and to the oleogel-network mechanical strength, with lower digestion extent in denser particle network. During the lipolysis process, smaller mixed micelles were formed when the particles were prepared using higher SO concentrations. Interestingly, an appreciable increase in the ꞵ-carotene bioaccessibility was observed, reaching maximum value at 10 %wt. SO, implying the effect of oil structuring on the ꞵ-carotene release process. Overall, these results suggest that the combination of solid texture and liquid lipid core in the oleogel particles offers mechanical protection and molecular micellization ability during digestion. Such characteristics can be utilized for effective encapsulation systems able to improve the bioaccessibility of hydrophobic molecules.

Blast mitigation analysis of novel designed sandwich structures using novel approaches

Sandwich panels have excellent explosion and impact resistance capabilities. Thus, by combining square and circular honeycombs in various ways, innovative blast-proof steel sandwich panels were developed in this numerical study. A series of dynamic explicit analyses were performed at 1 to 3 kg of TNT blasts for a constant stand-off distance (SoD) of 100 mm to identify an efficiently designed sandwich panel. Further work was carried out to achieve successive improvements in the efficiently designed steel sandwich panel’s blast mitigation performance by applying different patterns of Al foam filling and fiber metal laminate (FML) facing. The ability to absorb energy, core crushing, and face deflection under blast loadings were utilized to examine the novel designed sandwich panels’ blast resistance. The Johnson-Cook (J-C) model and Hashin’s and Puck-Schurmann’s criteria were applied to accurately determine the damage behavior of steel and composite parts of the structures, respectively. The obtained results showed that the combination of square and circular honeycomb cores in a sandwich construction significantly increased blast resistance for both layered and unlayered honeycomb cases compared to the standard square honeycomb core employed in the sandwich structure (S-SS). A further enhancement in blast resistance was seen when the bottom honeycomb core of layered honeycomb was filled with foam. The further employment of the FML top face highly advanced the blast performance of the novel designed sandwich panel, and it can be applied to various parts of armor vehicles to save soldiers’ lives from air-blasts.

Boosting Reaction Kinetics and Mass Transfer of Bifunctional Co‐Based Oxygen Electrocatalyst Prepared from CoAl‐LDH

AbstractThe simultaneous optimization of sluggish reaction kinetics and mass transfer in bifunctional oxygen electrocatalysts for air cathodes remains a great challenge. This study utilizes CoAl‐layered double hydroxide as a metal precursor to fabricate a bifunctional oxygen electrocatalyst, denoted as CoAlOXD‐Thin. This electrocatalyst features a specific core–shell structure of Co species, which grows on an aerophilic and conductive substrate composed of Al2O3 and carbon. It is successfully demonstrated that the thickness of Co@Co3O4 core–shell structure can be easily controlled by selecting different precursors and the combination of Co core and Co3O4 shell optimizes the adsorption strength of intermediates, leading to enhanced catalytic performance. Additionally, the Al species plays a dual role. It not only facilitates the mass transfer of oxygen species but also hinders the 2e− pathway of oxygen reduction reaction, leading to improved selectivity. Notably, the Zn–air batteries utilizing CoAlOXD‐Thin demonstrate an impressive peak power density of 216.2 mW cm−2, a high specific capacity of 800.8 mAh gZn−1, and excellent cycling stability and reversibility, surpassing those of the Pt/C + RuO2 catalyst. This study presents a novel approach to enhance air cathode performance by optimizing reaction kinetics and mass transfer through precursor design.

Liquid-Core-Microtubule-Enhanced Laser Sensor for High-Resolution Temperature Measurement

We present a fiber laser temperature sensor based on temperature dependence whisper gallery mode-based microcavity. Three different thermo-optic coefficient liquids are injected into a thin wall thickness microtubule for different temperature sensitivity of whisper gallery mode shift. The sensor temperature sensitivity increases with the absolute value of the liquid core thermo-optic coefficient. The theoretical model of whisper gallery mode temperature response is analyzed. A liquid core microtubule is inserted into the erbium-doped fiber ring laser cavity as the optical filter and sensing unit simultaneously, so the lasing wavelength can be used to detect the temperature change of the medium. Due to the narrow spectral width of sensing laser, a high sensing resolution system is experimentally confirmed. With the combination of liquid core to increase the sensitivity and fiber ring laser cavity to increase sensing resolution, the high sensitivity 112.8 pm/°C of sensing system is demonstrated and the thermal resolution is 8.16 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> °C.

Polyvinyl alcohol composite hydrogels/epoxidized natural rubber composites (CMCS/PVA/CS-ENR) with core-shell structure as biomass coating material for slow-release nitrogen fertilizer

Using natural rubber (NR)/chitosan (CS)/polyvinyl alcohol (PVA) as raw materials, biodegradable semi-IPN (semi-interpenetrating polymer network) composites were prepared by thiol-epoxy click reaction under UV light, which was used as the shell of sustained release preparation. Using polyvinyl alcohol (PVA)/carboxymethyl chitosan (CMCS) as raw material and vanillin as the cross-linking agent, hydrogen-bonded hybrid network hydrogel loaded with urea was prepared by freeze-thaw cycle, which was used as the core of sustained-release preparation. Finally, a green-coated urea fertilizer with core-shell structure was prepared to ameliorate the environmental pollution of slow-release fertilizer (for example, synthetic polymer-coated fertilizers are difficult to biodegrade), as well as to achieve the water retention and the effective slow-release. The high CS/PVA contents and the combination of the hydrogel core and the rubber shell significantly improved the mechanical properties of the coating material (tensile strength above 5 MPa, elongation at break up to 1400 %), hydrophilicity (to promote the degradation rate of the rubber shell) and soil water retention of the coating material (close to pure hydrogel), showing enhanced reaction. In terms of slow-release effect, coated nitrogen fertilizer with 3 % CS content, 5 % PVA content and 10-min coating time (SRP3/10) achieved the best slow-release effect of nitrogen (N) in water (62.7 % at 10 days), which was related to the hydrophilicity, semi-IPN skeleton and the cross-linking structure of the network, and the release conformed to the Korsmeyer-Peppas model with a non-Fickian diffusion release mechanism, indicating that the behavior of N release was mediated by a combination of drug diffusion and skeleton dissolution.

Stochastic three-dimensional numerical phantoms to enable computational studies in quantitative optoacoustic computed tomography of breast cancer.

When developing a new quantitative optoacoustic computed tomography (OAT) system for diagnostic imaging of breast cancer, objective assessments of various system designs through human trials are infeasible due to cost and ethical concerns. In prototype stages, however, different system designs can be cost-efficiently assessed via virtual imaging trials (VITs) employing ensembles of digital breast phantoms, i.e., numerical breast phantoms (NBPs), that convey clinically relevant variability in anatomy and optoacoustic tissue properties. The aim is to develop a framework for generating ensembles of realistic three-dimensional (3D) anatomical, functional, optical, and acoustic NBPs and numerical lesion phantoms (NLPs) for use in VITs of OAT applications in the diagnostic imaging of breast cancer. The generation of the anatomical NBPs was accomplished by extending existing NBPs developed by the U.S. Food and Drug Administration. As these were designed for use in mammography applications, substantial modifications were made to improve blood vasculature modeling for use in OAT. The NLPs were modeled to include viable tumor cells only or a combination of viable tumor cells, necrotic core, and peripheral angiogenesis region. Realistic optoacoustic tissue properties were stochastically assigned in the NBPs and NLPs. To advance optoacoustic and optical imaging research, 84 datasets have been released; these consist of anatomical, functional, optical, and acoustic NBPs and the corresponding simulated multi-wavelength optical fluence, initial pressure, and OAT measurements. The generated NBPs were compared with clinical data with respect to the volume of breast blood vessels and spatially averaged effective optical attenuation. The usefulness of the proposed framework was demonstrated through a case study to investigate the impact of acoustic heterogeneity on OAT images of the breast. The proposed framework will enhance the authenticity of virtual OAT studies and can be widely employed for the investigation and development of advanced image reconstruction and machine learning-based methods, as well as the objective evaluation and optimization of the OAT system designs.

Study on self-centering mechanism of different yield strength hybrid buckling restrained braces

Conventional buckling-restrained braces (BRBs) exhibit stable compressive and tensile strengths and excellent energy dissipation characteristics. Nevertheless, the low post-yield stiffness limits the capacity of BRBs to control the peak displacement of the structure. This leads to large residual displacements in structures, which increases the probability of collapse under strong earthquakes. Consequently, introducing a reliable system that dissipates seismic energy, and provides an adequate self-centering capability, is necessary. This study has been carried out to investigate the hybrid BRBs response with different yield strengths (DY-HBRB) using numerical analysis. The cyclic responses, residual displacement, energy dissipation, and equivalent damping coefficient of the DY-HBRB models have been assessed. A simplified core-spring finite element model was utilized to model DY-HBRB elements. Moreover, an innovative trilinear kinematic hysteresis (TKH) model is proposed to simulate the cyclic behavior and facilitate the application of DY-HBRBs to seismic designs. The proposed model has been validated with the experimental investigation and numerical analysis results. The results indicate that selecting appropriate combinations of steel cores with different yield strengths in DY-HBRB provides a stable cyclic response with adequate energy dissipation and eliminates a significant part of the residual displacement. In addition, it was confirmed that the proposed TKH model could logically represent the double yield point of the DY-HBRBs with remarkable precision.

One kilometer balanced analog photonic link based on a single multicore fiber

A one kilometer balanced microwave photonic link based on a single four core multicore optical fiber is demonstrated for the first time, to the best of our knowledge. The radio frequency gains and differential phase stabilities over temperature were measured and compared to a conventional balanced link based on two spans of single mode fiber. Both the multicore fiber link and the single mode fiber balanced link exhibited differential phase fluctuations of |Δφ|≤13° at 25 GHz (corresponding to a differential delay or skew, |Δt|, of ≤1.4ps) under identical periodic temperature oscillations of ±13°C over a 60 min period. In contrast, previous studies have shown that two single mode fiber spans should have exhibited up to an order of magnitude greater Δφs compared to the multicore fiber. Our different results can be attributed to how the fibers are arranged; the previous works kept the two single mode fiber spans separate, on different spools, whereas in this work the two single mode fiber spans were co-located as close as possible together by spooling them ‘side-by-side’ onto a single mandrel, more representative of a balanced link in application. In addition, the radio-frequency crosstalk between the multicore fiber’s cores were measured, exhibiting acceptable levels at least 60 dB below the signal for all core combinations. The crosstalk is shown to be dominated by occurrences at localized points, e.g. at the multiplexers (fan-in/fan-outs) and splices, rather than during propagation. Regardless of the single mode fiber link’s performance, the measurements here demonstrate that multicore fiber-based balanced links are a viable single fiber alternative to conventional dual single mode fiber-based balanced links.

Fibrosis entropy is associated with life-threatening arrhythmia in non-ischaemic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): This work was supported by the National Institute for Health Research Biomedical Research Centre at Guy’s and St. Thomas’ Trust and King’s College, the Centre of Excellence in Medical Engineering funded by the Wellcome Trust and Engineering and Physical Sciences Research Council (EPSRC; WT088641/Z/09/Z). M.J.B. is supported by a Medical Research Council New Investigator Grant (MR/N011007/1) and British Heart Foundation (Project grant PG/18/74/34077). This work was supported by EPSRC 2018/19 DTP - EP/R513064/1 grant. This work was supported by a National Heart and Lung Institute Foundation grant awarded to Professor Sanjay Prasad and Dr Richard Jones. Background Enhanced risk stratification for implanted defibrillator requirement represents an important area of research in patients with non-ischemic cardiomyopathy (NICM). Myocardial fibrosis represents the major underlying arrhythmic substrate in this population, and its identification on late-gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) is associated with life-threatening arrhythmia (LTA). Fibrosis entropy, a measure of scar texture heterogeneity, may confer important information regarding the underlying pro-arrhythmic mechanisms of both core scar and areas of intermediate signal intensity (Gray Zone [GZ]). Purpose We sought to: 1) evaluate whether LGE-CMR assessment of left ventricular (LV) tissue entropy had incremental utility to fibrosis presence for arrhythmic risk stratification of patients with NICM; 2) quantify the added utility of GZ entropy in such analysis. Methods This study involved a prospective observational cohort of consecutive patients with NICM and myocardial fibrosis detected on LGE-CMR. Epicardial and endocardial contours obtained from LGE-CMR data were used with a FWHM method to delineate core fibrosis (≥50% maximum signal intensity) and GZ fibrosis (≥35%-&amp;lt;50% signal intensity). Fibrotic masks were subsequently used, along with native dicom LGE-CMR images to compute tissue entropy, defined by the standard Shannon Entropy for core fibrosis, GZ fibrosis, and combined core+GZ fibrosis. Patients underwent adjudicated long-term follow-up for LTA (composite of sudden cardiac death, aborted sudden cardiac death or sustained ventricular tachycardia). Results Of 291 patients with NICM and mid-wall/subepicardial fibrosis, 38 patients (13.1%) experienced LTA over median follow-up of 6.3 years (interquartile range 4.6-9.1 years). On Cox regression analysis, core fibrosis entropy (Hazard ratio [HR] 1.77, 95% CI 1.25-2.54, p=0.001), GZ fibrosis entropy (HR 1.74, 95% CI 1.20-2.54, p=0.004) and combined fibrosis entropy (HR 1.98, 95% CI 1.30-2.52, p=0.001) were associated LTA after adjustment for variables used to guide ICD implantation (LVEF &amp;lt;35% and NYHA class &amp;gt;1) and remained associated in multivariable models accounting separately for core and GZ fibrosis mass. The addition of core fibrosis entropy, GZ fibrosis entropy and combined fibrosis entropy to a baseline clinical model improved the C-statistic from 0.49 to 0.59, 0.62 and 0.62, respectively. LVEF &amp;lt;35% was not associated with LTA (HR 1.45, 95% CI 0.77-2.74, p=0.25) on multivariable analysis. Conclusions Fibrosis entropy on LGE-CMR offers incremental utility to LVEF and fibrosis presence for arrhythmic risk prediction in patients with NICM. The combination of core and GZ fibrosis entropy offers the highest association with risk.

Microbial traces found in microdolomite associated with seep-related shallow gas hydrate

Recently, microdolomite grains with a diameter of about 30–150 μm were discovered within seep-related shallow gas hydrate in the eastern margin of the Japan Sea, and the preliminary assumption has been that their formation is mediated by microbially secreted extracellular polymeric substances (EPS). To verify this interpretation, the present study investigates the characteristics of minerals and organic matter inside the microdolomite grains. Observation by polarizing microscopy reveals that the microdolomite grains generally consist of combinations of distinct cores and external cements. The cores are mostly dark or cloudy and their abundance does not show clear depth dependence, while the external cements are generally isopachous in the shallow part and polygonal in the deeper portions. To further clarify the characteristics of these cores and external cements, thin-foil sections were prepared from two major types of microdolomite, one with a dark core and polygonal external cement, and one with a cloudy core and isopachous external cement. These thin-foil sections were then analyzed by scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). In the dark core, fibriform pores of about 100 nm diameter were observed to be closely related with amorphous calcium carbonate (ACC) and carboxy groups, likely created by heterogeneous nucleation on microbial EPS surfaces. The polygonal external cement is composed of monocrystalline dolomite, representing slow crystal growth in the deeper part where hydrate formation is less active. On the other hand, the observed cloudy core and the isopachous external cement are, respectively, composed of scattered and accumulated rhombohedral dolomite crystals, presumably resulting from homogeneous nucleation in saline pockets of rapidly growing hydrate and subsequent crystal accumulation on the surface of spherical oil films.