Cleavage Technique Research Articles

Acid-Triggered Side Chain Cleavage Leads to Doped Conjugated Polymers of High Conductivity.

Cleavable side chain based conjugated polymers (CSCPs) represent a unique approach to offering solution processability with added benefits via the elimination of insulating side chains. This work highlights an optimally designed polythiophene-carboxylic acid based CSCP, POET-T2-COOH, which achieves a conductivity exceeding 350 S/cm in molecularly doped and side chain cleaved films, 100-100,000 times higher than three other structurally isomeric CSCPs. The high conductivity of POET-T2-COOH is accomplished via a new "cleavage with doping" methodology, synergistically combining a strong acid and a primary dopant. This hybrid method achieves the greatest conductivity in all isomeric CSCPs over conventional doping or cleavage techniques. The doped and side chain cleaved POET-T2-COOH displays a stable conductivity in inert atmospheres and a high work function of 5.3 eV, opening up new applications.

Exploring surface properties and premelting in crystals.

Crystal surfaces play a pivotal role in governing various significant processes, such as adsorption, nucleation, wetting, friction, and wear. A fundamental property that influences these processes is the surface free energy, γ. We have directly calculated γ(T) for low-index faces of Lennard-Jones (LJ), germanium, and silicon crystals along their sublimation lines using the computational cleavage technique. Our calculations agree well with experimental values for Si(111) and Ge(111), highlighting the accuracy of the method and models used. For LJ crystals, we identified a premelting onset at Tpm = 0.75Tm, marked by a sharp increase in atom mobility within the second outermost surface layer. Notably, Tpm closely aligned with the endpoint of the LJ melting line at negative pressures, Tend = 0.76Tm. We hypothesize that the emergence and coexistence of a liquid film atop the LJ crystal at Tpm < T < Tm correspond to the metastable melting line under negative pressures experienced by stretched crystal surfaces. Furthermore, our study of thin LJ crystal slabs reveals that premelting-induced failure leads to recrystallization below the homogeneous freezing limit, offering a promising avenue to explore crystal nucleation and growth at extremely deep supercoolings. Finally, no evidence of premelting was detected in the model crystals of Ge and Si, which is consistent with the experimental observations. Overall, our findings offer valuable insights into crystal surface phenomena at the atomic scale.

An Alternative Technique For Intraocular Lens Removal: Bimanual Cleavage In The Vitreous Chamber

Purpose: We aimed to present a new technique for lens explantation, involving intraocular lens (IOL) cleavage in the vitreous chamber using two forceps and successive removal from the anterior chamber (AC). Methods: Retrospective mono-centric analysis of 10 eyes affected by IOL subluxation/luxation who underwent IOL explantation and 23G vitrectomy. After separating the capsular bag rests from the IOL using the vitrectomy probe, serrated forceps were used to grab the IOL, while microscissors performed an “initiation” cut at the midpoint of the lens plate. A second pair of serrated forceps grabbed the IOL plate on the other side. Then, the two forceps were slowly pulled one apart from the other, exerting a separative force perpendicular to the initiation cut and causing the IOL to cleave in two pieces. In case of asymmetric cleavage, a second cleavage was performed. The pieces of the IOL were then moved to the AC and removed through a clear corneal incision. Results: Intraoperative mean IOL removal time was 14.1±6.5 minutes. The IOLs (seven 1-piece and three 3-pieces IOLs) were successfully explanted with this technique in all patients. Overall, 4 cases underwent exclusive IOL explantation and the eyes were left aphakic. Postoperatively, BCVA improved in all patients at 1 week follow-up and no intraoperative or postoperative adverse events were reported. Cornea was completely clear in every case since postoperative day 1. Conclusion: Bimanual cleavage technique for IOL removal ensured safer IOL handling in the larger vitreous chamber and minimized the procedures to be performed in the AC.

New approaches to edge passivation of laser cut PERC solar cells

Recently the development trend in the PV industry is towards much larger wafer formats. With increasing wafer area and the resulting increase in short-circuit current at the cell level, there is also a trend towards sub-cells (solar cell cut into smaller pieces) for module integration. Using sub-cells, the resistance losses through the connection can be reduced. Modules based on sub-cells achieve higher levels of fill factors and thus a higher nominal power. However, the energy yield of such sub-cells is reduced compared to full cells due to the non-passivated laser edge. The laser cut edge causes a high recombination of the charge carriers, which negatively affects the pseudo fill factor as well as open-circuit voltage of the cell. The current work introduces two different approaches for passivating the laser separated PERC solar cells. The experiments were performed on p-type PERC monofacial cells and laser scribe and mechanical cleavage (LSMC) technique was used to obtain sub-cells from the host cells. The method ‘laser scribing and simultaneous Al doping’ increases the pFF of the cleaved cells by +0.2–0.4%abs in comparison to the reference cleaved cells whereas the method ‘laser scribing and subsequent Al doping’ shows an improvement in efficiency of the cleaved cells by + 0.2% abs.

Method of mechanical exfoliation of bismuth with micro-trench structures

The discovery of graphene led to a burst in search for 2D materials originating from layered atomic crystals coupled by van der Waals force. While bulk bismuth crystals share this layered crystal structure, unlike other group V members of the periodic table, its interlayer bonds are stronger such that traditional mechanical cleavage and exfoliation techniques have shown to be inefficient. In this work, we present a novel mechanical cleavage method for exfoliating bismuth by utilizing the stress concentration effect induced by micro-trench SiO2 structures. As a result, the exfoliated bismuth flakes can achieve thicknesses down to the sub-10 nm range, which are analyzed by atomic force microscopy and Raman spectroscopy.

Electrochemical C-H/C-C Bond Oxygenation: A Potential Technology for Plastic Depolymerization.

Herein, we provide eco-friendly and safely operated electrocatalytic methods for the selective oxidation directly or with water, air, light, metal catalyst or other mediators serving as the only oxygen supply. Heavy metals, stoichiometric chemical oxidants, or harsh conditions were drawbacks of earlier oxidative cleavage techniques. It has recently come to light that a crucial stage in the deconstruction of plastic waste and the utilization of biomass is the selective activation of inert C(sp3 )-C/H(sp3 ) bonds, which continues to be a significant obstacle in the chemical upcycling of resistant polyolefin waste. An appealing alternative to chemical oxidations using oxygen and catalysts is direct or indirect electrochemical conversion. An essential transition in the chemical and pharmaceutical industries is the electrochemical oxidation of C-H/C-C bonds. In this review, we discuss cutting-edge approaches to chemically recycle commercial plastics and feasible C-C/C-H bonds oxygenation routes for industrial scale-up.

Rapid and Sensitive Detection of Toxigenic Fusarium asiaticum Integrating Recombinase Polymerase Amplification, CRISPR/Cas12a, and Lateral Flow Techniques.

Fusarium head blight (FHB) is a global cereal disease caused by a complex of Fusarium species. Both Fusarium graminearum and F. asiaticum are the causal agents of FHB in China. F. asiaticum is the predominant species in the Middle-Lower Reaches of the Yangtze River (MLRYR) and southwest China. Therefore, detecting F. asiaticum in a timely manner is crucial for controlling the disease and preventing mycotoxins from entering the food chain. Here, we combined rapid genomic DNA extraction, recombinase polymerase amplification, Cas12a cleavage, and lateral flow detection techniques to develop a method for the rapid detection of F. asiaticum. The reaction conditions were optimized to provide a rapid, sensitive, and cost-effective method for F. asiaticum detection. The optimized method demonstrated exceptional specificity in detecting F. asiaticum while not detecting any of the 14 other Fusarium strains and 3 non-Fusarium species. Additionally, it could detect F. asiaticum DNA at concentrations as low as 20 ag/μL, allowing for the diagnosis of F. asiaticum infection in maize and wheat kernels even after 3 days of inoculation. The developed assay will provide an efficient and robust detection platform to accelerate plant pathogen detection.

Use of a Photocleavable Initiator to Characterize Polymer Chains Grafted onto a Metal Plate with the Grafting-from Method.

The thorough characterization of polymer chains grafted through a "grafting-from" process onto substrates based on the determination of number (Mn) and weight (Mw) average molar masses, as well as dispersity (Ɖ), is quite challenging. It requires the cleavage of grafted chains selectively at the polymer-substrate bond without polymer degradation to allow their analysis in solution with steric exclusion chromatography, in particular. The study herein describes a technique for the selective cleavage of PMMA grafted onto titanium substrate (Ti-PMMA) using an anchoring molecule that combines an atom transfer radical polymerization (ATRP) initiator and a UV-cleavable moiety. This technique allows the demonstration of the efficiency of the ATRP of PMMA on titanium substrates and verification that the chains were grown homogeneously.

Unique graphene‐carbon black hybrid nanofiller by a micromechanical cleavage technique as a reinforcing agent in elastomers: Fundamental and experimental studies

AbstractIn this work, a synthetic technique was developed which effected delamination of graphite into graphene with simultaneous disaggregation of carbon black clusters and formation of secondary attachment between the two. Styrene butadiene rubber nanocomposite with this hybrid filler exhibited substantial reinforcement in the mechanical properties, wear resistance and rubber‐filler interactions. The hybrid nanofiller was superior to conventional carbon black, imparting 57% increase in tensile strength of the nanocomposite. The composite with the hybrid filler also exhibited improved modulus and traction. A detailed analysis of mechanism of reinforcement by the hybrid filler is proposed by the computation of root mean square end‐to‐end network chain distance and the lateral tube dimension employing the entangled‐bound‐rubber‐tube (EBT) model. This neoteric hybrid nanofiller overcame the so‐called dispersibility issues and could be exploited as a part of replacement of carbon black, a synthetic material from fossil fuel by sustainable natural filler.

Target Recognition- and HCR Amplification-Induced In Situ Electrochemical Signal Probe Synthesis Strategy for Trace ctDNA Analysis.

An electrochemical-DNA (E-DNA) sensor was constructed by using DNA metallization to produce an electrochemical signal reporter in situ and hybridization chain reaction (HCR) as signal amplification strategy. The cyclic voltammetry (CV) technique was used to characterize the electrochemical solid-state Ag/AgCl process. Moreover, the enzyme cleavage technique was introduced to reduce background signals and further improve recognition accuracy. On the basis of these techniques, the as-prepared E-DNA sensor exhibited superior sensing performance for trace ctDNA analysis with a detection range of 0.5 fM to 10 pM and a detection limit of 7 aM. The proposed E-DNA sensor also displayed excellent selectivity, satisfied repeatability and stability, and had good recovery, all of which supports its potential applications for future clinical sample analysis.

Sensory Reconstruction of a Posterior Heel Defect Using a Proximally Based Sensate Medial Plantar Flap with Retrograde Nerve Cleavage Technique.

Reconstruction of posterior heel defects is important because it requires thick and durable skin that can withstand pressure and shear from shoe and bed contact. Therefore, the sensate flap could be a better option for the defect. This paper reports on the safety of a medial plantar sensory flap for these defects as well as an objective measurement of the sensation of the medial plantar flap and the plantar surface distal to the donor site. Twelve patients had soft-tissue defects in the posterior heel and underwent reconstructive surgery using a proximally based sensate medial plantar sensory flap. Cases of plantar defects involving not posterior heel were excluded. For wider flap coverage, special neurovascular dissection was required. We evaluated levels of sensation quantitatively using Semmes-Weinstein (SW) monofilaments and a two-point discriminator at the final follow-up. All flaps survived without major complications. Postoperative follow-up was 12 to 64 months (mean 26 months). All 12 flaps healed without postoperative complications. There was no significant difference in minimal two-point discrimination and SW evaluator size between the transferred medial plantar flap area and the contralateral heel area or between the plantar area distal to the donor site and the contralateral side. Patients could walk normally and sleep without protective shoes or brace. A proximally based sensate medial plantar flap is a good option for the reconstruction of posterior heel defects. It can restore the characteristics of the posterior heel for shoe wearing and sleeping.

Direct determination of Lennard-Jones crystal surface free energy by a computational cleavage method

The surface free energy of solids, γ, plays a crucial role in all physical and chemical processes involving material surfaces. For the first time, we obtained γ directly from molecular dynamics simulations using a crystal cleavage method. The approach was successfully realized in a Lennard-Jones system by inserting two movable external walls, each consisting of a single crystal layer, into a bulk crystal to create flat, defect-free surfaces. The cleavage technique designed allowed us to calculate the surface free energy according to its definition and avoid surface premelting. The temperature dependence of γ was determined for the (100) and (110) crystal planes along the whole sublimation line and its metastable extension, up to T = 1.02 · Tm, where Tm is the melting point. Good agreement with indirect values of γ(T) was found. The proposed computational cleavage method can be applied to other solids of interest, providing valuable insight into the understanding of chemical and physical surface processes, and demonstrates the successful import of the cleavage method, traditionally used in technical preparation and study of crystal surfaces, into a modern atomistic simulation.

ПРИКЛАДНЫЕ АСПЕКТЫ ТЕОРИИ РЕДУКЦИОННОГО АНАЛИЗА КАМЕННЫХ ИНДУСТРИЙ

In the process of manufacturing of stone tools and their subsequent intended use, they were intensively transformed and subjected to reduction. They sequentially changed their shape and decreased in their size. This technologically determined process applied equally to both lithic cores and tools. Regardless of the goals, stadium splitting (with changes in the cleavage technique, according to E. Giria) and permanent splitting were used. During the reduction, morphology of stone tools changed significantly. In many cases, this led to appearance of new types of lithic cores and tools. The genetic relationship between these types is revealed on the base of morphometric analysis and refitting-model data. Based on empirical observations, it is possible to determine a steady trend of changes in the types of stone tools during their intensive processing. The type of reduction should be understood as a stable vector of changes in shape of stone tools during sequential splitting or cyclical renewal of their working properties. The method of reduction analysis is applicable to stone industries not only of the Stone Age, but also of the Early Iron Age. Reduction analysis of stone industries is associated with two levels of generalization. The first of them concerns reduction sequences in splitting of lithic cores and making-renewal of stone tools. The second one is related to the degree of transformation of structure of entire complex of stone tools, depending on the depth of processing of stone raw materials. The type of reduction reflects not only the technological, but also the cultural context, i.e. the stylistic features of stone industry. They appeared in the case when there is a variable choice of technology or technique for solving the task of stone tools producing. Reduction analysis of stone industry provides additional arguments for functional diagnostics of Stone Age sites.

Evidence for the Cytoplasmic Localization of the L-α-Glycerophosphate Oxidase in Members of the "Mycoplasma mycoides Cluster".

Members of the “Mycoplasma mycoides cluster” are important animal pathogens causing diseases including contagious bovine pleuropneumonia and contagious caprine pleuropneumonia, which are of utmost importance in Africa or Asia. Even if all existing vaccines have shortcomings, vaccination of herds is still considered the best way to fight mycoplasma diseases, especially with the recent and dramatic increase of antimicrobial resistance observed in many mycoplasma species. A new generation of vaccines will benefit from a better understanding of the pathogenesis of mycoplasmas, which is very patchy up to now. In particular, surface-exposed virulence traits are likely to induce a protective immune response when formulated in a vaccine. The candidate virulence factor L-α-glycerophosphate oxidase (GlpO), shared by many mycoplasmas including Mycoplasma pneumoniae, was suggested to be a surface-exposed enzyme in Mycoplasma mycoides subsp. mycoides responsible for the production of hydrogen peroxide directly into the host cells. We produced a glpO isogenic mutant GM12::YCpMmyc1.1-ΔglpO using in-yeast synthetic genomics tools including the tandem-repeat endonuclease cleavage (TREC) technique followed by the back-transplantation of the engineered genome into a mycoplasma recipient cell. GlpO localization in the mutant and its parental strain was assessed using scanning electron microscopy (SEM). We obtained conflicting results and this led us to re-evaluate the localization of GlpO using a combination of in silico and in vitro techniques, such as Triton X-114 fractionation or tryptic shaving followed by immunoblotting. Our in vitro results unambiguously support the finding that GlpO is a cytoplasmic protein throughout the “Mycoplasma mycoides cluster.” Thus, the use of GlpO as a candidate vaccine antigen is unlikely to induce a protective immune response.

基于三明治SERS结构和酶剪切技术的肿瘤标志物miRNA-21的高灵敏检测

基于三明治SERS结构和酶剪切技术的肿瘤标志物miRNA-21的高灵敏检测

Practical Method for Accurate Determination of Alkylphenol Ethoxylates in Household Detergents by Aluminum Iodide Cleavage Pretreatment Followed by GC–MS

A practical procedure was developed for detecting nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) in household detergents by gas chromatography–mass spectrometry (GC–MS) with the introduction of a cleavage technique using aluminum iodide (AlI3) to convert NPEOs and OPEOs to their parent nonylphenol and octylphenol. The reliability of the cleavage process was evaluated using Igepal-210, Triton X-15, Tergitol NP-9, and Triton X-100 as substrates, demonstrating satisfactory efficiency. The effect of the sample matrix on the cleavage process was investigated, and the optimized dose of AlI3 was estimated. The major advantage of this method is the use of a common analytical tool (GC–MS) for accurate monitoring of APEOs after elimination of the ethoxylate chain, with detection limits of 12.5 mg/kg and 5.0 mg/kg for NPEO9 and OPEO9, respectively. Analytical results revealed that NPEOs and OPEOs were found in 12.6 % of 182 household detergents in the concentration range of 18–800 mg/kg.

Two-Dimensional Cadmium Chloride Nanosheets in Cadmium Telluride Solar Cells.

In this study we make use of a liquid nitrogen-based thermomechanical cleavage technique and a surface analysis cluster tool to probe in detail the tin oxide/emitter interface at the front of completed CdTe solar cells. We show that this thermomechanical cleavage occurs within a few angstroms of the SnO2/emitter interface. An unexpectedly high concentration of chlorine at this interface, ∼20%, was determined from a calculation that assumed a uniform chlorine distribution. Angle-resolved X-ray photoelectron spectroscopy was used to further probe the structure of the chlorine-containing layer, revealing that both sides of the cleave location are covered by one-third of a unit cell of pure CdCl2, a thickness corresponding to about one Cl-Cd-Cl molecular layer. We interpret this result in the context of CdCl2 being a true layered material similar to transition-metal dichalcogenides. Exposing cleaved surfaces to water shows that this Cl-Cd-Cl trilayer is soluble, raising questions pertinent to cell reliability. Our work provides new and unanticipated details about the structure and chemistry of front surface interfaces and should prove important to improving materials, processes, and reliability of next-generation CdTe-based solar cells.

Surfactant-Free Polar-to-Nonpolar Phase Transfer of Exfoliated MoS2 Two-Dimensional Colloids.

Exfoliation of lamellar materials into their corresponding layers represented a breakthrough, owing to the outstanding properties arising from the nanometric thickness confinement. Among the cleavage techniques, liquid-phase exfoliation is now on the rise because it is scalable and leads to easy-to-manipulate colloids. However, all appropriate exfoliating solvents exhibit strong polarity, which greatly restricts the scope of feasible functionalization or processing of the resulting flakes. Here, this scope is extended: nanosheets exfoliated in a polar medium are demonstrated to properly disperse in a nonpolar solvent. To that purpose, suspensions of molybdenum disulfide flakes were prepared in isopropanol/water and a phase transfer of the nanosheets to chloroform was developed by flocculation and redispersion/centrifugation sequences, without any assisting surfactant. The colloidal stability of the nanosheets in chloroform was found to be governed by their lateral dimensions and, although lower than in polar media, proved to be high enough to open the way to subsequent functionalization or processing of the flakes in nonpolar media.

Use of the phaco tip technique for lens cleavage and removal during cataract surgery.

Use of the phaco tip technique for lens cleavage and removal does not require manual hydrodissection using a syringe and cannula, or cortical removal using an irrigation/aspiration tip. The phaco tip is the only surgical instrument required for this technique. Its advantages include maintaining a stable intraocular pressure during cortical cleaving hydrodissection and lens removal, which includes the cortex.

Multiplex, Rapid, and Sensitive Isothermal Detection of Nucleic-Acid Sequence by Endonuclease Restriction-Mediated Real-Time Multiple Cross Displacement Amplification.

We have devised a novel isothermal amplification technology, termed endonuclease restriction-mediated real-time multiple cross displacement amplification (ET-MCDA), which facilitated multiplex, rapid, specific and sensitive detection of nucleic-acid sequences at a constant temperature. The ET-MCDA integrated multiple cross displacement amplification strategy, restriction endonuclease cleavage and real-time fluorescence detection technique. In the ET-MCDA system, the functional cross primer E-CP1 or E-CP2 was constructed by adding a short sequence at the 5′ end of CP1 or CP2, respectively, and the new E-CP1 or E-CP2 primer was labeled at the 5′ end with a fluorophore and in the middle with a dark quencher. The restriction endonuclease Nb.BsrDI specifically recognized the short sequence and digested the newly synthesized double-stranded terminal sequences (5′ end short sequences and their complementary sequences), which released the quenching, resulting on a gain of fluorescence signal. Thus, the ET-MCDA allowed real-time detection of single or multiple targets in only a single reaction, and the positive results were observed in as short as 12 min, detecting down to 3.125 fg of genomic DNA per tube. Moreover, the analytical specificity and the practical application of the ET-MCDA were also successfully evaluated in this study. Here, we provided the details on the novel ET-MCDA technique and expounded the basic ET-MCDA amplification mechanism.