BINA

Platinum group metal‐free catalysts have been considered the most promising alternative for platinum‐based catalysts for the oxygen reduction reaction in fuel cells. Despite the significant advancement made in activity, their viability as fuel cell catalysts is still questionable due to their low durability. So far, deciphering the degradation mechanisms of this class of catalysts has been hampered by their undefined structure. Herein, we used a molecular model catalyst, iron‐phthalocyanine, featuring Fe−N4 active sites with resemblance to those in the more active Fe−N−C catalysts, and studied their degradation mechanisms. Based on X‐ray photoelectron spectroscopy and the electrochemical measurements, three main demetallation processes were identified: at potentials higher than 0.65 V vs. RHE, where the metal center is Fe3+, an electrochemical oxidation of the ligand ring is occurring, between 0.6 and 0.2 V …

T-cell diversity is crucial for producing effective receptors that can recognize the pathogens encountered throughout life. A stochastic biological process known as VDJ recombination accounts for the high diversity of these receptors, making their analysis challenging. We present a new approach to sequence encoding and analysis, based on the Lempel-Ziv 76 algorithm (LZ-76). By creating a graph-like model, we identify specific sequence features and produce a new encoding approach to an individual's repertoire. We demonstrate that this repertoire representation allows for various applications, such as generation probability inference, informative feature vector derivation, sequence generation, and a new measure for diversity estimation.

Chaos, namely exponential sensitivity to initial conditions, is generally considered a nuisance, inasmuch as it prevents long‐term predictions in physical systems. Here, an easily accessible approach to undo deterministic chaos and tailor ray trajectories in arbitrary 2D optical billiards by introducing spatially varying refractive index therein is presented. A new refractive index landscape is obtained by a conformal mapping, which makes the trajectories of the chaotic billiard fully predictable and the billiard fully integrable. Moreover, trajectory rectification can be pushed a step further by relating chaotic billiards with non‐Euclidean geometries. Two examples are illustrated by projecting billiards built on a sphere as well as the deformed spacetime outside a Schwarzschild black hole, which respectively lead to all periodic orbits and spiraling trajectories remaining away from the boundaries of the transformed 2D billiards …

Oxygen reduction reaction (ORR) is considered the bottleneck reaction in fuel cells. Its sluggish kinetics requires the use of scarce and expensive platinum group metal (PGM) catalysts. Significant efforts have been invested in trying to find a PGM‐free catalyst to replace Pt for this reaction or reduce its loadings. One interesting family of materials that has shown great promise in doing so is aerogels, which are based on covalent frameworks. The aerogels’ high surface area and porosity enable good mass transport and high catalyst utilization that is expected to lower PGM loadings or replacing them completely. This review summarizes recent research in this field, introducing methods of using aerogels as cathodes for ORR, from carbon to metal aerogels. The catalytic sites vary from nanoparticles to atomically dispersed metal ions embedded in carbon aerogels that form all‐in‐one platform which can serve as both …

Chiral polymeric particles (CPPs) were studied extensively in recent years due to their importance in pharmaceutical applications. Here, nanosized CPPs were synthesized and applied as catalysts for direct asymmetric aldol reaction. The CPPs were prepared by miniemulsion or inverse miniemulsion based on various chiral amino acid derivatives and characterized by dynamic light scattering and scanning electron microscopy. The nanoparticles with spherical structure between 250 and 400 nm and high chiral surface area were used as catalysts in the aldol reaction at room temperature without additional solvent. L-tryptophan gave the highest enantiomeric excess, >86% with similar catalytic performance four times.

Ultrasonic irradiation of molten metals in liquid media causes dispersion of the metals into suspensions of micro- and nano- particles that can be separated. This is applicable mainly to low-mp elemental metals or alloys, but higher mp were also reported. Among the metals, mercury and gallium exhibit especially-low melting points thus considered as liquid metals (LM). Sonication of mercury in aqueous solutons of certain metal-ions can cause simultaneous reduction of the ions and reactions between the metals. Gallium can be melted and sonicated in warm water, as-well-as in aqueous solutions of various solutes such as metal ions and organic compounds, which opened a wide window of interactions between the gallium particles and the solutes. Sonication of molten metals in organic liquids, such as polyethylene glycole (PEG) 400, forms carbon dots (C-dots) doped with nanoparticles of these metals. This …

Detection of target molecules, such as proteins, antibodies, or specific DNA sequences, is critical in medical laboratory science. Commonly used assays rely on tagging the target molecules with fluorescent probes. These are then fed to high-sensitivity detection systems. Such systems typically consist of a photodetector or camera and use time-resolved measurements that require sophisticated and expensive optics. Magnetic modulation biosensing (MMB) is a novel, fast, and sensitive detection technology that has been used successfully to detect viruses such as Zika and SARS-CoV-2. While this powerful tool is known for its high analytical and clinical sensitivity, the current signal-processing method for detecting the target molecule and estimating its dose is based on time-resolved measurements only. To improve the MMB-system performance, we propose here a novel signal processing algorithm that uses both temporally and spatially resolved measurements. We show that this combination significantly improves the sensitivity of the MMB-based assay. To evaluate the new method statistically, we performed multiple dose responses of Human Interleukin 9 (IL -8) on different days. Compared to standard time-resolved methods, the new algorithm provides a 2-3 fold improvement in detection limit and a 25% improvement in quantitative resolution.

The development of vacuum‐deposited perovskite materials and devices is partially slowed down by the minor research effort in this direction, due to the high cost of the required research tools. But there is also another factor, thermal co‐deposition in high vacuum involves the simultaneous sublimation of several precursors with an overall deposition rate in the range of few Å s−1. This leads to a deposition time of hours with only a single set of process parameters per batch, hence to a long timeframe to optimize even a single perovskite composition. Here we report the combinatorial vacuum deposition of wide bandgap perovskites using 4 sources and a non‐rotating sample holder. By using small pixel substrates, more than 100 solar cells can be produced with different perovskite absorbers in a single deposition run. The materials are characterized by spatially resolved methods, including optical, morphological …

Pelvic organ prolapse (POP) is a dysfunction that affects a large proportion of women. Current support scaffolds’ lack of biocompatibility, biodegradability, and mechanical compliance are associated with surgical complications including erosion and pain, indicating the urgent need for new tissue scaffolds with customizable functions. A new material that uses polyvinyl alcohol (PVA) as the main ingredient and is chemically tuned to possess suitable mechanical properties and degradation rates for the surgical treatment of POP is developed. Specifically, the thiol‐norbornene “click” chemistry enables the sol‐gel transition of the biomaterial under UV‐light without side‐products. Meanwhile, NaOH treatment further toughens the hydrogel with a higher crosslink density. The PVA‐based biocompatible ink can be printed with UV‐facilitated direct ink writing due to the rapidly UV‐initiated chemical crosslink; in situ image …

Millions of adenosines are deaminated throughout the transcriptome by ADAR1 and ADAR2, modulating double-stranded RNA (dsRNA) immunogenicity and recoding mRNA. The high variability in the susceptibility of different adenosines to editing begs the question of what are the determinants of substrate specificity. Here, we systematically monitor how secondary structure modulates ADAR2 vs ADAR1 substrate selectivity, on the basis of systematic probing of thousands of synthetic sequences transfected into ADAR1-deleted cell lines exogenously expressing either ADAR2 or ADAR1. In both cases, structural disruptions gave rise to symmetric, strand-specific induced editing at a fixed offset, but of varying length: -26 nt for ADAR2, and -35 nt for ADAR1. We dissect the basis for the differences in offset between ADAR1 and ADAR2 via diverse mutants, domain-swaps, and ADAR evolutionary homologs, and reveal that it is encoded by the differential RNA binding domain architecture. We demonstrate that this offset-enhanced editing can allow an improved design of ADAR2-recruiting therapeutics, with proof-of-concept experiments suggestive of increased on-target and potentially decreased off-target editing. Our findings provide novel insight into the determinants guiding ADAR2 substrate selectivity and into the roles of the RNA binding domains of ADAR1 and ADAR2 in mediating differential targeting, and should facilitate the design of improved ADAR-recruiting therapeutics.

Gold-containing nanoparticles are proven to be an effective radiosensitizer in the radiotherapy of tumors. Reliable imaging of nanoparticles in a tumor and surrounding normal tissues is crucial both for diagnostics and for nanoparticle application as radiosensitizers. The Fe3O4 core was introduced into gold nanoparticles to form a core/shell structure suitable for MRI imaging. The aim of this study was to assess the in vivo bimodal CT and MRI enhancement ability of novel core/shell Fe3O4@Au theranostic nanoparticles. Core/shell Fe3O4@Au nanoparticles were synthesized and coated with PEG and glucose. C57Bl/6 mice bearing Ca755 mammary adenocarcinoma tumors received intravenous injections of the nanoparticles. CT and MRI were performed at several timepoints between 5 and 102 min, and on day 17 post-injection. Core/shell Fe3O4@Au nanoparticles provided significant enhancement of the tumor and tumor blood vessels. Nanoparticles also accumulated in the liver and spleen and were retained in these organs for 17 days. Mice did not show any signs of toxicity over the study duration. These results indicate that theranostic bimodal Fe3O4@Au nanoparticles are non-toxic and serve as effective contrast agents both for CT and MRI diagnostics. These nanoparticles have potential for future biomedical applications in cancer diagnostics and beyond.

Animal food source production is increasing due to the growing world population. Many sources (e.g., hay) are prone to mold development, resulting in food degradation. This study proposes an environmentally friendly anti-mold fungicide comprising hydrogen peroxide (HP) and thymol entrapped in a polyvinyl alcohol/pyrrolidone (PVA/PVP) hydrogel (PVA is biodegradable and PVP is water soluble and non-toxic) coated on a polyethylene (PE) films for preservative hay packaging. The hydrogels improved the thermal stability of the entrapped HP and thymol, resulting in a prolonged release into the hay and thereby increasing anti-mold activity. The hydrogel composition and morphology, thymol and HP thermal stability, and release rates through indirect (gas phase) contact were investigated. Fungicidal capabilities were tested, indicating wide-range efficiency against mold growth on hay with a clear advantage for the thymol-loaded hydrogels. No visual side effects were observed on hay exposed to the released fumes of HP and/or thymol. These results demonstrate the potential of thymol-loaded hydrogels as effective and safe post-harvest preservatives.

We demonstrate strong coupling between a single or few J-aggregates and an inverse bowtie plasmonic structure, when the J-aggregate is located at a specific axial distance from the metallic surface. Three hybrid modes are clearly observed, witnessing a strong interaction, with a Rabi splitting of up to 290 meV, the precise value of which significantly depends on the orientation of the J-aggregate with respect to the symmetry axis of the plasmonic structure. We repeated our experiments with a set of triangular hole arrays, showing consistent formation of three or more hybrid modes, in good agreement with numerical simulations.

Laser micromachining is the chosen method for vertical interconnect access point (VIA) formation in flex PCB layers. Even so, this method suffers from several inherent physical issues as a result of the intense localized heating causing strong Marangoni convection and the buildup of recast along the VIA upper crater walls while also scattered particle debris and oxidation of copper across the surface. The mitigation of the height and radius of this recast layer is critical for the following build-up process and device functionality and reliability. This is currently a major technology inhibitor to the adoption of flex PCBs for high-power electronics. In this study, we present experimental results showing the use of engineered sacrificial layers that coat the surface of the flex PCB substrate during the laser micromachining process. Optimization of this engineered sacrificial layer resulted in a major improvement in recast quality and debris control as well as reducing the oxide formation while increasing the laser drilling efficiency, attributable to increased surface pressure on the substrate. In this paper, we describe the methods and materials used in the development of sacrificial layers and show the positive impact it achieves on improving and modifying the plasma characteristics throughout the overall laser drilling process.

Fluorescent nanocarbons are well-proficient nanomaterials because of their optical properties and surface engineering. Herein, Apium graveolens-derived carbon dots (ACDs) have been synthesized by a one-step hydrothermal process without using any surplus vigorous chemicals or ligands. ACDs were captured via an in situ gelation reaction to form a semi-interpenetrating polymer network system showing mechanical robustness, fluorescent behavior, and natural adhesivity. ACDs-reinforced hydrogels were tested against robust uniaxial stress, repeated mechanical stretching, thixotropy, low creep, and fast strain recovery, confirming their elastomeric sustainability. Moreover, the room-temperature self-healing behavior was observed for the ACDs-reinforced hydrogels, with a healing efficacy of more than 45%. Water imbibition through hydrogel surfaces was digitally monitored via “breathing” and “accelerated …

Disordered metallic nanostructures have features that are not realized in well‐defined nanometallic counterparts, such as broadband light localization and inhomogeneous refraction index at the nanoscale. Disordered metal systems with a networked inner architecture have both particles and voids with subwavelength dimensions which are randomly 3D organized in space. These disordered structures are benefited from high surface area and damage stability, permit guest materials permeability, and can be achieved in large scales employing less costs and expertise. Their abundant nanosize gaps and sharp tips can interact with incident light over a broadband range to generate a rich pattern of hot‐spots and can therefore function as an artificial leaf, for example. Here, the linear and nonlinear optical properties of both well‐defined and disordered plasmonic structures are reviewed with a focus on largescale 3D …

Sensitive serological assays are needed to provide valuable information about acute and past viral infections. For example, detection of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies could serve as the basis for an “immunity passport” that would enable individuals to travel internationally. Here, utilizing a novel Magnetic Modulation Biosensing (MMB) system and the receptor-binding domain of the SARS-CoV-2 spike protein, we demonstrate a highly sensitive and specific anti-SARS-CoV-2 IgG serological assay. Using anti-SARS-CoV-2 IgG antibodies, RT-qPCR SARS-CoV-2-positive and healthy patients’ samples, and vaccinees’ samples, we compare the MMB-based SARS-CoV-2 IgG assay’s analytical and clinical sensitivities to those of the enzyme-linked immunosorbent assay (ELISA). Compared with ELISA, the MMB-based assay has an ~6-fold lower limit of detection (129 ng/L vs. 817 ng/L), and it detects an increase in the IgG concentration much earlier after vaccination. Using 85 RT-qPCR SARS-CoV-2-positive samples and 79 -negative samples, the MMB-based assay demonstrated similar clinical specificity (98% vs. 99%) and sensitivity (93% vs. 92%) to the ELISA test, but with a much faster turnaround time (45 min vs. 245 min). The high analytical and clinical sensitivity, short turnaround time, and simplicity of the MMB-based assay makes it a preferred method for antibody detection.

We report on stabilization of Li-S cells with different types of composite sulfur cathodes using ethereal LiTFSI/LiNO3/DOL/DME electrolyte solutions containing a-priori 0.1M Li2S8. These electrolyte solutions enable an improved cycling behavior for Li-S cells compared to Li2S8-free electrolyte solutions, thanks to the presence of LiSx species from the beginning of operation. We show that Li anodes cycled in Li|S cells with solutions containing Li2S8 possess flatter and more uniform surface, higher dimensions of the surface structures in average and, as a result, a lower surface area. This surface morphology ensures a low rate of parasitic surface reactions of the electrolyte components on the Li anodes’ surface, slower depletion of the electrolyte solution in the cells and stabilization of the cells cycling. Besides, the presence of Li2S8 maintains a better integrity of composite sulfur/carbon/PVdF cathodes, ensuring a …

In this study, we characterized diabetic retinopathy in two mouse models and the response to anti-vascular endothelial growth factor (VEGF) injection. The study was conducted in 58 transgenic, non-obese diabetic (NOD) mice with spontaneous type 1 diabetes (n = 30, DMT1-NOD) or chemically induced (n = 28, streptozotocin, STZ-NOD) type 1 diabetes and 20 transgenic db/db mice with type 2 diabetes (DMT2-db/db); 30 NOD and 8 wild-type mice served as controls. Mice were examined at 21 days for vasculopathy, retinal thickness, and expression of genes involved in oxidative stress, angiogenesis, gliosis, and diabetes. The right eye was histologically examined one week after injection of bevacizumab, ranibizumab, saline, or no treatment. Flat mounts revealed microaneurysms and one apparent area of tufts of neovascularization in the diabetic retina. Immunostaining revealed activation of Müller glia and prominent Müller cells. Mean retinal thickness was greater in diabetic mice. RAGE increased and GFAP decreased in DMT1-NOD mice; GFAP and SOX-9 mildly increased in db/db mice. Anti-VEGF treatment led to reduced retinal thickness. Retinas showed vasculopathy and edema in DMT1-NOD and DMT2-db/db mice and activation of Müller glia in DMT1-NOD mice, with some response to anti-VEGF treatment. Given the similarity of diabetic retinopathy in mice and humans, comparisons of type 1 and type 2 diabetic mouse models may assist in the development of new treatment modalities.

Atrial fibrillation (AF) is a major cause of morbidity and mortality. Current guidelines support performing electrocardiogram (ECG) screenings to spot AF in high-risk patients. The purpose of this study was to validate a new algorithm aimed to identify AF in patients measured with a recent FDA-cleared contact-free optical device.