Substitution Effect of a Single Nitrogen Atom on π-Electronic Systems of Linear Polycyclic Aromatic Hydrocarbons (PAHs): Theoretically Visualized Coexistence of Mono- and Polycyclic π-Electron Delocalization.

We theoretically investigated the nitrogen substitution effect on the molecular structure and π-electron delocalization in linear nitrogen-substituted polycyclic aromatic hydrocarbons (N-PAHs). Based on the optimized molecular structures and magnetic field-induced parameters of fused bi- and tricyclic linear N-PAHs, we found that the local π-electron delocalization of subcycles (e.g., mono- and bicyclic constituent moieties) in linear N-PAHs is preserved, despite deviation from ideal structures of parent monocycles. The introduction of a fused five-membered ring with a pyrrolic N atom (N-5MR) in linear N-PAHs significantly perturbs the π-electronic condition of the neighboring fused six-membered ring (6MR). Monocyclic pyrrole exhibits substantial bond length alternations, strongly influencing the π-electronic systems of both the fused N-5MR and 6MR in linear N-PAHs, depending on the location of shared covalent bonds. A fused six-membered ring with a graphitic N atom in an indolizine moiety cannot generate monocyclic π-electron delocalization but instead contributes to the formation of polycyclic π-electron delocalization. This is evidenced by bifurcated diatropic ring currents induced by an external magnetic field. In conclusion, the satisfaction of Hückel's 4n + 2 rule for both mono- and polycycles is crucial for understanding the overall π-electron delocalization. It is crucial to consider the unique characteristics of the three types of substituted N atoms and the spatial arrangement of 5MR and 6MR in N-PAHs.

Failure Modes of Flexible LiCoO2 Cathodes Incorporating Polyvinylidene Fluoride Binders with Different Molecular Weights.

Understanding the mechanical failure modes of lithium-ion battery [Li-ion batteries (LIBs)] electrodes is exceptionally important for enabling high specific energy and flexible LIB technologies. In this work, the failure modes of lithium cobalt oxide (LCO) cathodes under repeated bending and the role of the polymer binder in improving the mechanical durability of the LCO electrodes for use in flexible LIBs are investigated. Mechanical and electrochemical evaluations of LCO electrodes (areal capacity of ≥2.5 mA h cm-2) employing poly(vinylidene fluoride) (PVDF) binder were carried out, followed by extensive optical and electron microscopies. We find that the molecular weight (MW) of the PVDF significantly influenced the surface and bulk microstructure of the LCO electrodes, particularly the distribution of carbon additive and binder, which plays a crucial role in affecting the mechanical and electrochemical properties of the electrodes. Multiple mechanical failure modes (e.g., surface scratches and microcracks) observed in the LCO electrodes subjected to repeated bending originated from the use of low MW PVDF; these failure modes were successfully mitigated by using a high MW PVDF. Remarkably, the optimized flexible LCO electrode incorporating high MW PVDF showed comparable discharge capacity retention during galvanostatic cycling after repeated bending (7000 cycles at 50 mm bending diameter) to electrodes not subjected to the repeated bending. This study highlights the importance of carrying out a comprehensive investigation of the failure mechanisms in flexible electrodes, which identified the pivotal role of the PVDF MW in the electrode microstructure and its effects on the electrode resilience to failure during repeated bending.

Electroacupuncture for abdominal pain relief in patients with acute pancreatitis: A three-arm randomized controlled trial.

BACKGROUND: Electroacupuncture (EA) may reduce the severity of acute pancreatitis (AP) and provide additional pain relief in patients with chronic pancreatitis. However, the ability of EA to relieve pain in patients with AP has not been well documented. OBJECTIVE: This study was undertaken to compare the pain-relieving effects of EA and conventional treatment in patients with AP. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS: This study was conducted using a randomized, controlled, three-arm, parallel-group and multi-center design. Patients diagnosed with AP were randomly and equally assigned to EA1, EA2 or control groups. All participants received conventional standard-of-care therapy for AP. Local EA alone was administered in EA1, and local plus distal EA was given in EA2. Local EA included two abdominal acupoints, while distal EA included twelve peripheral acupoints. EA groups underwent one session of EA daily for 4 days (days 1-4), or until pain was resolved or discharged. MAIN OUTCOME MEASURES: The primary outcome measure was the change in the visual analogue scale (VAS; 0-100) pain score between baseline and day 5. RESULTS: Eighty-nine participants were randomized into EA1, EA2 and control groups, and 88 (EA1, 30; EA2, 29; control, 29) were included in the full-analysis set. VAS score change (median [interquartile range]) on day 5 was (12.3 ± 22.5) in the EA1 group, (10.3 ± 21.5) in the EA2 group, and (8.9 ± 15.2) in the control group. There were not significant differences in the change in VAS score among treatments (P = 0.983). However, time to food intake was significantly shorter in the EA group (EA1 + EA2) than in the control group (median 2.0 days vs 3.0 days), with a hazard ratio of 0.581 (P = 0.022; 95% CI, 0.366-0.924). No significant adverse events occurred. CONCLUSION: EA treatment did not significantly reduce pain after 4 days of treatment in patients with AP-associated abdominal pain but significantly reduced time to first food intake. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT03173222. Please cite this article as: Jang DK, Lee JK, Jung CY, Kim KH, Kang HR, Lee YS, Yoon JH, Joo KR, Chae MK, Baek YH, Seo BK, Lee SH, Lim C. Electroacupuncture for abdominal pain relief in patients with acute pancreatitis: A three-arm randomized controlled trial. J Integr Med. 2023; 21(6): 537-542.

Detection of triclosan using 2-domain hemoglobin promoter of Daphnia magna.

Triclosan has been widely used as an antimicrobial agent. However, triclosan was found to cause toxicity, including muscle contraction disturbances, carcinogenesis, and endocrine disorders. In addition, it was found to affect central nervous system function adversely and even have ototoxic effects. Conventional methods for detecting such triclosan can be performed easily. However, the conventional detection methods are inadequate in precisely reflecting the impact of toxic substances on stressed organisms. Therefore, a test model for the toxic environment at the molecular level through the organism is needed. From that point of view, Daphnia magna is being used as a ubiquitous model. D. magna has the advantages of easy cultivation, a short lifespan and high reproductive capacity, and high sensitivity to chemicals. Therefore, the protein expression pattern of D. magna that appear in response to chemicals can be utilized as biomarkers for detecting specific chemicals. In this study, we characterized the proteomic response of D. magna following triclosan exposure via two-dimensional (2D) gel electrophoresis. As a result, we confirmed that triclosan exposure completely suppressed D. magna 2-domain hemoglobin protein and evaluated this protein as a biomarker for triclosan detection. We constructed the HeLa cells in which the GFP gene was controlled by D. magna 2-domain hemoglobin promoter, which under normal conditions, expressed GFP, but upon triclosan exposure, suppressed GFP expression. Consequently, we consider that the HeLa cells containing the pBABE-HBF3-GFP plasmid developed in this study can be used as novel biomarkers for triclosan detection.

Laser-based three-dimensional manufacturing technologies for rechargeable batteries.

Laser three-dimensional (3D) manufacturing technologies have gained substantial attention to fabricate 3D structured electrochemical rechargeable batteries. Laser 3D manufacturing techniques offer excellent 3D microstructure controllability, good design flexibility, process simplicity, and high energy and cost efficiencies, which are beneficial for rechargeable battery cell manufacturing. In this review, notable progress in development of the rechargeable battery cells via laser 3D manufacturing techniques is introduced and discussed. The basic concepts and remarkable achievements of four representative laser 3D manufacturing techniques such as selective laser sintering (or melting) techniques, direct laser writing for graphene-based electrodes, laser-induced forward transfer technique and laser ablation subtractive manufacturing are highlighted. Finally, major challenges and prospects of the laser 3D manufacturing technologies for battery cell manufacturing will be provided.

Zinc Phosphides as Outstanding Sodium-Ion Battery Anodes.

To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP2 and Zn3P2) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics were evaluated. The Na reactivity of ZnP2 was better than that of Zn3P2. Therefore, a C-modified ZnP2-based composite (ZnP2-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP2-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP2 in the composite was transformed into NaZn13 and Na3P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn13 and Na3P, respectively, were fully recombined to the original ZnP2 phase during desodiation. Owing to the one-step conversion/recombination of ZnP2 in the composite during cycling, the ZnP2-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g-1 after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g-1 at 1 C and 350 mA h g-1 at 3 C.

Direct Visualization of Lithium Polysulfides and Their Suppression in Liquid Electrolyte.

Understanding of lithium polysulfide (Li-PS) formation and the shuttle phenomenon is essential for practical application of the lithium/sulfur (Li/S) cell, which has superior theoretical specific energy (2600 Wh/kg). However, it suffers from the lack of direct observation on behaviors of soluble Li-PS in liquid electrolytes. Using in situ graphene liquid cell electron microscopy, we have visualized formation and diffusion of Li-PS simultaneous with morphological and phase evolutions of sulfur nanoparticles during lithiation. We found that the morphological changes and Li-PS diffusion are retarded by ionic liquid (IL) addition into electrolyte. Chronoamperometric shuttle current measurement confirms that IL addition lowers the experimental diffusion coefficient of Li-PS by 2 orders of magnitude relative to that in IL-free electrolyte and thus suppresses the Li-PS shuttle current, which accounts for better cyclability and Coulombic efficiency of the Li/S cell. This study provides significant insights into electrolyte design to inhibit the polysulfide shuttle phenomenon.

Three-Dimensionally Aligned Sulfur Electrodes by Directional Freeze Tape Casting.

Rational design of sulfur electrodes is exceptionally important in enabling a high-performance lithium/sulfur cell. Constructing a continuous pore structure of the sulfur electrode that enables facile lithium ion transport into the electrode and mitigates the reconstruction of sulfur is a key factor for enhancing the electrochemical performance. Here, we report a three-dimensionally (3D) aligned sulfur electrode cast onto conventional aluminum foil by directional freeze tape casting. The 3D aligned sulfur-graphene oxide (S-GO) electrode consisting of few micron thick S-GO layers with 10-20 µm interlayer spacings demonstrates significant improvement in the performance of the Li/S cell. Moreover, the freeze tape cast graphene oxide electrode exhibits homogeneous reconfiguration behavior in the polysulfide catholyte cell tests and demonstrated extended cycling capability with only 4% decay of the specific capacity over 200 cycles. This work emphasizes the critical importance of proper structural design for sulfur-carbonaceous composite electrodes.

Freeze-Dried Sulfur-Graphene Oxide-Carbon Nanotube Nanocomposite for High Sulfur-Loading Lithium/Sulfur Cells.

The ambient-temperature rechargeable lithium/sulfur (Li/S) cell is a strong candidate for the beyond lithium ion cell since significant progress on developing advanced sulfur electrodes with high sulfur loading has been made. Here we report on a new sulfur electrode active material consisting of a cetyltrimethylammonium bromide-modified sulfur-graphene oxide-carbon nanotube (S-GO-CTA-CNT) nanocomposite prepared by freeze-drying. We show the real-time formation of nanocrystalline lithium sulfide (Li2S) at the interface between the S-GO-CTA-CNT nanocomposite and the liquid electrolyte by in situ TEM observation of the reaction. The combination of GO and CNT helps to maintain the structural integrity of the S-GO-CTA-CNT nanocomposite during lithiation/delithiation. A high S loading (11.1 mgS/cm2, 75% S) S-GO-CTA-CNT electrode was successfully prepared using a three-dimensional structured Al foam as a substrate and showed good S utilization (1128 mAh/g S corresponding to 12.5 mAh/cm2), even with a very low electrolyte to sulfur weight ratio of 4. Moreover, it was demonstrated that the ionic liquid in the electrolyte improves the Coulombic efficiency and stabilizes the morphology of the Li metal anode.

Toxicity detection using lysosomal enzymes, glycoamylase and thioredoxin fused with fluorescent protein in Saccharomyces cerevisiae.

Saccharomyces cerevisiae is the simplest and a favorite eukaryotic system that contains lysosome and thus, is a suitable organism for monitoring some toxic effects in environmental pollution. In this study, S. cerevisiae was transformed with two recombinant plasmids. Sporulation-specific glycoamylase (SGA1), which was upregulated in response to arsenic, was fused with the blue fluorescent protein (BFP) for the construction of an oxidative stress-causing chemicals sensor. Additionally, thioredoxin (TRX2), a protein overexpressed exclusively under tetracycline's influence, fused with the cyan fluorescent protein (CFP) to create a detector for this kind of chemical. In summary, we developed two recombinant S. cerevisiae that facilitate the detection of both kinds of toxic chemicals, specifically visualized by different color indicators.

Lithium Sulfide (Li2S)/Graphene Oxide Nanospheres with Conformal Carbon Coating as a High-Rate, Long-Life Cathode for Li/S Cells.

In recent years, lithium/sulfur (Li/S) cells have attracted great attention as a candidate for the next generation of rechargeable batteries due to their high theoretical specific energy of 2600 W·h kg(-1), which is much higher than that of Li ion cells (400-600 W·h kg(-1)). However, problems of the S cathode such as highly soluble intermediate species (polysulfides Li2Sn, n = 4-8) and the insulating nature of S cause poor cycle life and low utilization of S, which prevents the practical use of Li/S cells. Here, a high-rate and long-life Li/S cell is proposed, which has a cathode material with a core-shell nanostructure comprising Li2S nanospheres with an embedded graphene oxide (GO) sheet as a core material and a conformal carbon layer as a shell. The conformal carbon coating is easily obtained by a unique CVD coating process using a lab-designed rotating furnace without any repetitive steps. The Li2S/GO@C cathode exhibits a high initial discharge capacity of 650 mA·h g(-1) of Li2S (corresponding to the 942 mA·h g(-1) of S) and very low capacity decay rate of only 0.046% per cycle with a high Coulombic efficiency of up to 99.7% for 1500 cycles when cycled at the 2 C discharge rate.

Scalable synthesis of silicon nanosheets from sand as an anode for Li-ion batteries.

The silicon nanostructure is a promising candidate for an anode of Li-ion batteries due to its high theoretical capacity. In this work, we have demonstrated the scalable synthesis of Si nanosheets from natural sand by magnesiothermic reduction, and suggested a new formation mechanism for Si nanosheets. In the suggested mechanism, an Mg2Si intermediate phase was formed at an early stage of the reduction process, which leads to the two-dimensional Si nanostructure. The synthesized Si nanosheets have a leaf-like sheet morphology ranging from several ten to several hundred nanometers, and show comparable electrochemical properties to the commercial Si nanopowder as an anode for lithium ion batteries. For the improved electrochemical performance, Si nanosheets are encapsulated with reduced graphene oxide (RGO), and the RGO-encapsulated Si nanosheet electrode exhibits high-reversible capacity and excellent rate capability.