Insertion Mechanism Research Articles

Surgical management of rectal foreign bodies: A single-center experience.

Rectal foreign bodies (RFBs) are one of the rare clinical presentations in colorectal surgical practice, with an increasing incidence over the recent years. Due to the lack of standardized treatment options, the management of RFBs can be chal-lenging. This study aimed to evaluate our diagnostic and therapeutic approach to RFBs and to suggest a management algorithm. All patients with RFBs who hospitalized between January 2010 and December 2020 were retrospectively reviewed. Patient demographics, RFB insertion mechanism, inserted objects, diagnostic findings, management, complications, and outcomes were all evaluated. An algorithm for clinical management was developed depending on the center's experience. The cohort consisted of 21 patients, 17 (81%) were males. The median age was 33 years (ranging, 19-71). Sexual prefer-ences were the reason for RFB in 15 (71.4%) patients. In 17 (81%) patients, the RFB size over 10 cm. In 4 (19%) patients, RFBs were removed transanally without anesthesia in the emergency department; in the remaining 17 (81%), they were removed under anesthesia. Among these, RFBs were removed transanally under general anesthesia in 2 (9.5%) patients; with the assistance of a colonoscope under anesthesia in 8 (38%) patients; by milking towards the transanal route during laparotomy in 3 (14.2%) patients; and with the Hartmann procedure without restoration of bowel continuity in 4 (19%) patients. The median hospital stay was 6 days (ranging, 1-34 days). The Clavien-Dindo grade III-IV complication rate was 9.5%, and no post-operative mortality was observed. RFBs can usually be successfully removed transanally in the operating room with appropriate anesthetic technique and proper surgical instrument selection.

Selectivity of Electrochemical Ion Insertion into Manganese Dioxide Polymorphs

The ion insertion redox chemistry of manganese dioxide has diverse applications in energy storage, catalysis, and chemical separations. Unique properties derive from the assembly of Mn-O octahedra into polymorphic structures that can host protons and nonprotonic cations in interstitial sites. Despite many reports on individual ion-polymorph couples, much less is known about the selectivity of electrochemical ion insertion in MnO2. In this work, we use density functional theory to holistically compare the electrochemistry of AxMnO2 (where A = H+, Li+, Na+, K+, Mg2+, Ca2+, Zn2+, Al3+) in aqueous and nonaqueous electrolytes. We develop an efficient computational scheme demonstrating that Hubbard-U correction has a greater impact on calculating accurate redox energetics than choice of exchange-correlation functional. Using PBE+U, we find that for nonprotonic cations, ion selectivity depends on the oxygen coordination environments inside a polymorph. When H+ is present, however, the driving force to form hydroxyl bonds is usually stronger. In aqueous electrolytes, only three ion-polymorph pairs are thermodynamically stable within water's voltage stability window (Na+ and K+ in α-MnO2, and Li+ in λ-MnO2), with all other ion insertion being metastable. We find Al3+ may insert into the δ, R, and λ polymorphs across the full 2-electron redox of MnO2 at high voltage; however, electrolytes for multivalent ions must be designed to impede the formation of insoluble precipitates and facilitate cation desolvation. We also show that small ions coinsert with water in α-MnO2 to achieve greater coordination by oxygen, while solvation energies and kinetic effects dictate water coinsertion in δ-MnO2. Taken together, these findings explain reports of mixed ion insertion mechanisms in aqueous electrolytes and highlight promising design strategies for safe, high energy density electrochemical energy storage, desalination batteries, and electrocatalysts.

Methodological Studies of the Mechanism of Anion Insertion in Nanometer-Sized Carbon Micropores.

Dual-ion hybrid capacitors (DIHCs) are a promising class of electrochemical energy storage devices intermediate between batteries and supercapacitors, exhibiting both high energy and power density, and generalizable across wide chemistries beyond lithium. In this study, a model carbon framework material with a periodic structure containing exclusively 1.2 nm width pores, zeolite-templated carbon (ZTC), was investigated as the positive electrode for the storage of a range of anions relevant to DIHC chemistries. Screening experiments were carried out across 21 electrolyte compositions within a common stable potential window of 3.0-4.0 V vs. Li/Li+ to determine trends in capacity as a function of anion and solvent properties. To achieve fast rate capability, a binary solvent balancing a high dielectric constant with a low viscosity and small molecular size was used; optimized full-cells based on LiPF6 in binary electrolyte exhibited 146 Wh kg-1 and >4000 W kg-1 energy and power densities, respectively.

Charge Carriers for Aqueous Dual-Ion Batteries.

Environmental and safety concerns of energy storage systems call for application of aqueous battery systems which have advantages of low cost, environmental benignity, safety, and easy assembling. Among the aqueous battery systems, aqueous dual-ion batteries (ADIBs) provide high possibility for achieving excellent battery performance. Compared with the "rocking chair" batteries with only one type of carrier involved in the charging and discharging, ADIBs with both cations and anions as charge carriers possess diverse selections of electrodes and electrolytes. Charge carriers are the basis of the configuration of ADIBs. In this Review, cations and anions that could be applied in ADIBs are demonstrated with corresponding electrode materials and favorable electrolytes. Some insertion mechanisms are emphasized to provide insights for the possibilities to enhance the practical performances of ADIBs.

Copper-Catalyzed Boroaminomethylation of Olefins to γ-Boryl Amines with CO as C1 Source.

Boroaminomethylation of olefins is an efficient process to convert hydrocarbons directly into boron-, nitrogen-containing molecules. Such chemicals are a good handle for obtaining more complexed amine derivatives through the various transformations of organoboron. However, using simple and easily available CO as the C1 feedstock to achieve boroaminomethylation is still elusive. Here we report a copper-catalyzed boroaminomethylation of olefins with CO as the C1 source via the mechanism of a carbene insertion into the N-H bond. This method affords valuable γ-boryl amines from four inexpensive readily chemicals. The wide synthetic transformations of the γ-boryl amines demonstrates their utility. Notably, 13 C labeling studies revealed that the -CH2 -building block was derived from one molecule of CO.

Copper‐Catalyzed Boroaminomethylation of Olefins to γ‐Boryl Amines with CO as C1 Source

AbstractBoroaminomethylation of olefins is an efficient process to convert hydrocarbons directly into boron‐, nitrogen‐containing molecules. Such chemicals are a good handle for obtaining more complexed amine derivatives through the various transformations of organoboron. However, using simple and easily available CO as the C1 feedstock to achieve boroaminomethylation is still elusive. Here we report a copper‐catalyzed boroaminomethylation of olefins with CO as the C1 source via the mechanism of a carbene insertion into the N−H bond. This method affords valuable γ‐boryl amines from four inexpensive readily chemicals. The wide synthetic transformations of the γ‐boryl amines demonstrates their utility. Notably, 13C labeling studies revealed that the −CH2‐building block was derived from one molecule of CO.

(Invited) Potassium (co)Intercalation in Graphite: How Electrolyte Concentration May Trigger Different Cation Insertion Mechanisms

Recently, potassium-ion batteries (KIB) have been considered as a potential alternative of Li-ion batteries due to the cost effectiveness and the variety of electrode materials. Graphite – the well-known anode in LIB – has gained numerous attention from KIB scientists owing to its ability of intercalating K+ ion to form KC8 with high theoretical capacity (278 mAh/g) and good cycling retention.KFSI in DME has been considered as a promising electrolyte for KIB due to its compatibility with not only K metal but also the electrode materials. However, the electrolyte concentration strongly affects the electrochemistry of graphite. A change in the intercalating species as increasing the salt concentration, going from the cointercalation of [K(DME)x]+ (observed at 1M) to the simple intercalation of bare K+ ions (at 5M), was confirmed by galvanostatic profiles and operando XRD.By a complementary theoretical-experimental approach combining Raman spectroscopy with quantum chemistry, we provide here an insightful and coherent explanation of the occurring of the two different mechanisms, showing that they depend upon the solvation of K+ ions in DME rather than on the different SEI formed, as usually observed in lithium batteries.In some specific conditions, it was also possible to observe the co-existence of the two mechanisms, with the partial formation of staged intercalated-cointercalated layers, proving without doubt that the nature of the solvated species can be a major driving force driving specific ion insertion mechanisms.

Kinetics of Coupled Ion-Electron Transfer for Li-Ion Intercalation

Understanding the microscopic mechanism of Li-ion insertion in intercalation solids is crucial for the design of energy storage devices with optimal power and energy densities. Li intercalation kinetics has been traditionally treated by the phenomenological Butler-Volmer kinetics, but remains poorly measured and understood. For example, reported lithium intercalation kinetics for LiCoO2 in carbonate-electrolytes vary by 4-5 orders of magnitude. In this study, we developed experimental electrochemical methods for Li+-concentration-dependent Tafel kinetic measurements, and showed that the current of intercalation in LixCoO2 and NMCs was proportional to the fraction of empty Li+ sites. Exchange current densities and reorganization energies were also extracted for various electrode and electrolyte combinations. These results provide unique experimental evidence to support the microscopic mechanism of Li+ intercalation, where the electron and ion transfers are described by the theory of coupled ion-electron transfer (CIET). The proposed ion intercalation mechanism was also validated through the rate-dependent discharge capacity for eight electrode materials including LiFePO4 and graphite, which decreases linearly with the increasing discharge current under reaction-limited conditions. Our findings suggest that the proposed mechanism applies to a variety of intercalation materials used in energy storage, and governs the power density at low and moderate applied current densities. The possibility of modifying the reaction-limited current with electrodes and electrolytes opens new directions for interfacial engineering of Li-ion batteries.

N -Heterocycles Extended π-Conjugation Enables Ultrahigh Capacity, Long-Lived, and Fast-Charging Organic Cathodes for Aqueous Zinc Batteries

<i>N</i> -Heterocycles Extended π-Conjugation Enables Ultrahigh Capacity, Long-Lived, and Fast-Charging Organic Cathodes for Aqueous Zinc Batteries

Extended Insertion Functions for Opacity Enforcement in Discrete-Event Systems

Opacity is a confidentiality property that holds if certain secret behavior of a system, typically represented by a predicate, cannot be revealed under any system evolution. Among other proposed methodologies, when opacity is violated, it can be enforced using insertion mechanisms, i.e., by inserting symbols before an actual system output (in real time as the system evolves) in order to replace observation sequences that lead to opacity violations with observation sequences that can be generated by system behavior that does not violate opacity. This article focuses on opacity enforcement in discrete-event systems modeled with finite-state automata and proposes an extended insertion mechanism that can enforce opacity in a practical manner to a wide class of systems by inserting symbols before and after an actual system output. This article also introduces event insertion constraints that require only certain specific symbols to be inserted before and after an actual system output. For each case, we obtain a necessary and sufficient condition (based on the construction of an appropriate verifier) for opacity enforceability using the proposed extended insertion mechanism and devise a pertinent extended insertion strategy.

610 Evaluating the mechanism of amino acid insertion upon readthrough of cystic fibrosis transmembrane conductance regulator nonsense mutations

610 Evaluating the mechanism of amino acid insertion upon readthrough of cystic fibrosis transmembrane conductance regulator nonsense mutations

Insights on the proton mechanism in carbonyl-based organic electrode of neutral aqueous battery

Implementing proton insertion/removal in an aqueous battery has advantages like high safety, high rate, and low-temperature properties. The proton energy storage materials are mainly based on inorganic material in a strong acid electrolyte. Proton batteries attract much attention under neutral condition, especially based on the metal-free organic electrode. However, the proton concentration of neutral electrolyte is very low, and the proton insertion mechanism is not well understood. Herein, we firstly uncover the special energy storage mechanism of carbonyl materials as proton acceptor in neutral electrolyte. Carbonyl groups adsorb water molecular and induce proton insertion, this diffusion-free mechanism determines its fast reaction kinetics, which helps to improve the power density. Released OH− during proton insertion creates a local alkaline environment, which broadens the electrochemical window and contributes to the high energy density. With the structural diversity and tunability of carbonyl group, this special mechanism indicates that carbonyl-based organic materials are potential electrode for low-cost and high-performance neutral aqueous battery in the future.

YfeX - A New Platform for Carbene Transferase Development with High Intrinsic Reactivity.

Carbene transfer biocatalysis has evolved from basic science to an area with vast potential for the development of new industrial processes. In this study, we show that YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases, due to its high intrinsic reactivity, especially for the N-H insertion reaction of aromatic and aliphatic primary and secondary amines. YfeX shows high stability against organic solvents (methanol and DMSO), greatly improving turnover of hydrophobic substrates. Interestingly, in styrene cyclopropanation, WT YfeX naturally shows high enantioselectivity, generating the trans product with 87 % selectivity for the (R,R) enantiomer. WT YfeX also catalyzes the Si-H insertion efficiently. Steric effects in the active site were further explored using the R232A variant. Quantum Mechanics/Molecular Mechanics (QM/MM) calculations reveal details on the mechanism of Si-H insertion. YfeX, and potentially other peroxidases, are exciting new targets for the development of improved carbene transferases.

Facile preparation of hexagonal WO3 nanopillars and its reduced graphene oxide nanocomposites for high-performance supercapacitor

One-dimensional (1D) nanostructures are extremely important due to better charge transport capabilities. The ability to anchor 1D semiconductor nanostructures on graphene may give advantages in electrochemical charge storage applications. In this study, the authors explored the synthesis, growth mechanism, and insertion-type pseudocapacitive properties of 1D hexagonal (h) phase-WO3 (h-WO3) nanopillars and h-WO3/rGO nanocomposite. The nanocomposite is composed of h-WO3 nanopillars uniformly grown on a reduced graphene oxide (rGO) matrix and the resulting h-WO3/rGO nanocomposite shows the hexagonal structure and, 3D networks gathered during a hydrothermal process. XRD confirms the phase purity and crystalline nature, SEM confirms the hexagonal bundled nanopillar morphology of h-WO3 and its graphene composites, and rGO offered crumpled two-dimensional sheet-like morphologies. HRTEM and SAED analysis confirmed the highly oriented growth of h-WO3 nanowire along the [001] zone axis. XPS analysis confirms the presence of tungsten in +6 and + 5 oxidation states, indicating the formation of the oxygen-deficient h-WO3-x structure. The electrochemical characterizations are performed using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and stability tests. From the CV measurements, the outperformed exceptional h-WO3 and h-WO3/rGO nanocomposites exhibit specific capacitance (Csp) of ∼545 Fg−1 and ∼926 Fg−1, respectively, at a 5 mVs−1 scan rate, and from GCD measurements Csp found to be ∼504 Fg−1 and ∼991 Fg−1, respectively at 0.1 Ag−1 current density. Supercapacitor capacitances with carbon and metal oxide electrodes are typically related to the accessible surface areas. However, this work indicates that proton insertion, a rare capacitive charge storage mechanism, may significantly increase the capacitance of metal oxides with a limited surface area but a particular structure. Nonetheless, using the proton insertion process, scientists have shown that the electrodes made from an assembly structure of h-WO3 nanopillars have enhanced charge storage performance. According to detailed investigations, the electrochemical behavior of h-WO3 is dominated by the proton insertion mechanism and is critical in achieving high capacitance by eliminating alternative mechanisms. This research work presents a novel method for attaining extraordinary charge storage contribution into the ordered tunnels in crystalline metal oxides due to efficient proton insertion, which is especially significant for the construction of high-performance electrochemical energy storage systems: batteries and supercapacitors.

The Biogenesis of Multipass Membrane Proteins.

Multipass membrane proteins contain two or more α-helical transmembrane domains (TMDs) that span the lipid bilayer. They are inserted cotranslationally into the prokaryotic plasma membrane or eukaryotic endoplasmic reticulum membrane. The Sec61 complex (SecY complex in prokaryotes) provides a ribosome docking site, houses a channel across the membrane, and contains a lateral gate that opens toward the lipid bilayer. Model multipass proteins can be stitched into the membrane by iteratively using Sec61's lateral gate for TMD insertion and its central pore for translocation of flanking domains. Native multipass proteins, with their diverse TMDs and complex topologies, often also rely on members of the Oxa1 family of translocation factors, the PAT complex chaperone, and other poorly understood factors. Here, we discuss the mechanisms of TMD insertion, highlight the limitations of an iterative insertion model, and propose a new hypothesis for multipass membrane protein biogenesis based on recent findings.

Achieving high-energy and long-cycling aqueous zinc-metal batteries by highly reversible insertion mechanisms in Ti-substituted Na0.44MnO2 cathode

The tunnel-type sodium manganese oxide (Na0.44MnO2) materials are considered as promising cathode candidates for rechargeable batteries due to their low cost and sustainability. However, the direct implementation in aqueous batteries, as an emerging energy storage technology, was not fully realized in terms of the reversibility and long-cycling stability. Herein, the tunnel-type Ti-substituted Na0.44MnO2 (NMTO) is investigated as a cathode material for aqueous zinc-metal batteries. It is identified that the Ti-substitution has a significant effect on improving its rate capability and cycling stability. As a result, the optimal Na0.44Mn0.78Ti0.22O2 (NMTO-0.22) material exhibits a reversible capacity of 109.6 mAh/g at 1.0 A g−1, and 71% of the initial capacity can be retained after 2400 cycles. Such performance can be attributed to the enhanced insertion mechanisms in the tunnel structure, as verified by the post-mortem spectroscopic and microscopic techniques. Density functional theory (DFT) calculations enclose that the average charge density in Mn 3d orbits near the Fermi level and Mn participation in redox reaction are improved after Ti-substitution, supporting the facilitated electrochemical kinetics of NMTO. This work demonstrates that the Ti-substituted Na0.44MnO2 is a promising cathode material for aqueous zinc-metal batteries, and provides a fundamental understanding on the charge storage mechanisms.

Anisotropic damage model for collagenous tissues and its application to model fracture and needle insertion mechanics.

The analysis of tissue mechanics in biomedical applications demands nonlinear constitutive models able to capture the energy dissipation mechanisms, such as damage, that occur during tissue deformation. Furthermore, implementation of sophisticated material models in finite element models is essential to improve medical devices and diagnostic tools. Building on previous work toward microstructure-driven models of collagenous tissue, here we show a constitutive model based on fiber orientation and waviness distributions for skin that captures not only the anisotropic strain-stiffening response of this and other collagen-based tissues, but, additionally, accounts for tissue damage directly as a function of changes in the microstructure, in particular changes in the fiber waviness distribution. The implementation of this nonlinear constitutive model as a user subroutine in the popular finite element package Abaqus enables large-scale finite element simulations for biomedical applications. We showcase the performance of the model in fracture simulations during pure shear tests, as well as simulations of needle insertion into skin relevant to auto-injector design.

Perforin-2 clockwise hand-over-hand pre-pore to pore transition mechanism

Perforin-2 (PFN2, MPEG1) is a pore-forming protein that acts as a first line of defense in the mammalian immune system, rapidly killing engulfed microbes within the phagolysosome in macrophages. PFN2 self-assembles into hexadecameric pre-pore rings that transition upon acidification into pores damaging target cell membranes. Here, using high-speed atomic force microscopy (HS-AFM) imaging and line-scanning and molecular dynamics simulation, we elucidate PFN2 pre-pore to pore transition pathways and dynamics. Upon acidification, the pre-pore rings (pre-pore-I) display frequent, 1.8 s−1, ring-opening dynamics that eventually, 0.2 s−1, initiate transition into an intermediate, short-lived, ~75 ms, pre-pore-II state, inducing a clockwise pre-pore-I to pre-pore-II propagation. Concomitantly, the first pre-pore-II subunit, undergoes a major conformational change to the pore state that propagates also clockwise at a rate ~15 s−1. Thus, the pre-pore to pore transition is a clockwise hand-over-hand mechanism that is accomplished within ~1.3 s. Our findings suggest a clockwise mechanism of membrane insertion that with variations may be general for the MACPF/CDC superfamily.

Vat Orange 7 as an organic electrode with ultrafast hydronium-ion storage and super-long life for rechargeable aqueous zinc batteries

Organic electrode materials (OEMs) with various advantages are attracting much attention. However, the serious dissolution problem of OEMs has puzzled people for many years without being fundamentally addressed. Here, an aqueous Zn-ion battery using organic bisbenzimidazo[2,1-b:2′,1′-i]benzo[lmn][3,8]phenanthroline-8,17-dione (BBPD, also known as Vat Orange 7) as cathode material is developed. Due to the special H3O+ charge carrier insertion mechanism, both the BBPD and its discharged product H2BBPD as covalent compounds are not soluble in aqueous electrolytes, which make active materials integrity during long term cycles. Moreover, the special one-dimensional (1-D) square ion tunnels structure of the BBPD enables fast ion and electron transfer abilities in three dimensional directions, leading to an outstanding rate capability and power density. The assembled aqueous Zn-BBPD battery displays high rate performance (76.4 % capacity retention from 0.78 C to 153.85 C), excellent power density (13.4 kW kg−1) and capacity retention of 90.7 % after 10,000 cycles at 153.85 C. The kinetic and thermodynamic investigations on the exact dissolution mechanism of OEMs are first carried out in this work.

Stepwise Artificial Yarn Muscles with Energy-Free Catch States Driven by Aluminum-Ion Insertion.

Present artificial muscles have been suffering from poor actuation step precision and the need of energy input to maintain actuated states due to weak interactions between guest and host materials or the unstable structural changes. Herein, these challenges are addressed by deploying a mechanism of reversible faradaic insertion and extraction reactions between tetrachloroaluminate ions and collapsed carbon nanotubes. This mechanism allows tetrachloroaluminate ions as a strong but dynamic "locker" to achieve an energy-free high-tension catch state and programmable stepwise actuation in the yarn muscle. When powered off, the muscle nearly 100% maintained any achieved contractile strokes even under loads up to 96,000 times the muscle weight. The actuation mechanism allowed the programmable control of stroke steps down to 1% during reversible actuation. The isometric stress generated by the yarn muscle (14.6 MPa in maximum, 40 times that of skeletal muscles) was also energy freely lockable and step controllable with high precision. Importantly, when fully charged, the muscle stored energy with a high capacity of 102 mAh g-1, allowing the muscle as a battery to power secondary muscles or other devices.