Clamp Method Research Articles

The Effects of Phenanthrene on Electrical Activity in Ventricular Cardiomyocytes of Atlantic Cod (<i>Gadus morhua</i>)

The production of oil on the Arctic shelf and its transport along the Northern Sea Route increase risks of pollution of the ecosystems in the Arctic seas with oil and oil products. Today, polyaromatic hydrocarbons are known as the most toxic oil components, and phenanthrene is predominant in terms of its concentration in oil and physiological effects. Phenanthrene affects the electrical activity of fish heart, but its effects are species-specific. At the same time, the effects of phenanthrene on cardiac function in Arctic fishes, including economically important commercial species, are studied not enough. This study examines the effects of phenanthrene on electrical activity and ionic currents in ventricular myocardium of Atlantic cod (Gadus morhua). The major ionic currents in cod myocardium were IKr, IK1, INa and ICa. Phenanthrene (1 μM) did not affect the duration of action potentials (APs) recorded in isolated cod ventricular cardiomyocytes using patch clamp method. Meanwhile, phenanthrene suppressed rapid delayed rectifier current IKr by 61.33 ± 3.94%, decreasing the repolarization reserve of the myocardium. Phenanthrene did not affect nor the level of resting membrane potential, not background inward rectifier current IK1. Also, application of phenanthrene decreased AP upstroke velocity in cod myocytes, which was due to the suppression of fast sodium current INa. Finally, phenanthrene slightly reduced the amplitude of calcium current ICa and accelerated its inactivation, which overall led to the decrease in ICa charge transfer. Thus, the effects of phenanthrene on cod myocardium at cellular level can be described as potentially proarrhythmic, which makes the populations of cod in Arctic seas vulnerable to pollution of the aquatic environment by oil components after oil spills due to technological disasters.

Establishing a Whole-Cell Configuration through the Patch Clamp Method

Establishing a Whole-Cell Configuration through the Patch Clamp Method

Implementasi Teknik Sambung Pucuk untuk Meningkatkan Produktivitas dan Keberlanjutan Tanaman Buah Lokal Duku (Lansium domesticum) di Desa Arisan Buntal, Sumatera Selatan

Arisan Buntal Village is a small village in South Sumatra's Ogan Komering Ilir district. Duku (Lansium domesticum Corr) is a highly valued commodity in Arisan Buntal. The most significant barrier to straw development in Arisan Buntal is a need for high-quality seeds. Duku are traditionally grown; therefore, they take a long time to produce fruit. As a result, more advanced stitching techniques, such as the grafting technique, are required. However, because the youth of Arisan Buntal knew nothing about it and did not practice it, they tended to abandon the attempt down the business. This activity seeks to provide instruction in the Samsung puck technique production to the Arisan Buntal youth, allowing them to get superior duke crops and encouraging the sustainability of duke crops at the activity site. The evaluation of the activities revealed that the training participants improved their knowledge of duku-related commodities and grafting techniques. The post-test findings showed that 100% of the participants were aware of Arisan Buntal Village's potential as a hub for the growth of duku farming and the clamping method for duku crops. Furthermore, as many as 94% of participants had already tried the procedure with the assistance of specialists. Furthermore, the percentage of participants who prefer to apply the grafting method to the front has increased from 76.5% to 91.7%. The observation shows that the success rate of this technique reached 80%.

Exploration of steel slag by lignin and sodium citrate modification for mechanical properties and stability of steel slag-cement cementitious materials

Steel slag is produced globally in huge annual quantities. How to achieve its large-scale utilization is a question that researchers have been exploring. In this work, sodium citrate (SC) was used as a linker to modify Steel slag (SS) with alkali lignin (AL). And steel slag cement cementitious materials (CSS) were prepared with 10% replacement ratio. The effects of AL and SC on CSS were investigated by X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermo-gravimetric analysis (TG/DTA) etc. The results indicated that AL successfully loaded on the surface of SS. For CSS, as the degree of modification increased, the standard consistency water consumption of CSS decreased from 27% to 23.5%. During the hydration of CSS, its main hydration product was Ca(OH)2, the suitable amounts of AL and SC can stimulate the activity of SS. In addition, SS modification could improve the stability of CSS. The results of Ray's clamp method showed that the addition of AL and SC made the expansion of CSS reduced from 1.5 to 0. The 3 d and 28 d of CSS maximum flexural strengths were 5.42 MPa and 8.61 MPa and the maximum compressive strengths were 22.96 MPa and 49.15 MPa, respectively. This was an increase of 36.67% and 48.27% respectively. Therefore, the combination of AL and SS can not only effectively solve the problem of AL resource utilization, but also is expected to realize the practical application of SS in cement cementitious materials. It has good social and environmental benefits.

Research on grinding parameter optimization based on adhesive semiconductor quartz disc

Abstract To study the influence of grinding parameters on the grinding force of semiconductor quartz disc based on the adhesive clamping method, an orthogonal experiment was designed to investigate the impact of grinding parameters on the grinding force. Based on the orthogonal test data, the influencing factors and parameter optimization of the grinding force are developed. The experimental results show that the order of influence of grinding parameters on the X-axis is feed speed > spindle speed > grinding depth, the sequence of effect on the grinding force in the Y-axis is grinding depth > feed speed > spindle speed, and the order of influence on the grinding force in Z-axis is grinding depth > spindle speed > feed speed. Therefore, using a higher spindle speed, a lower feed rate and a shallower grinding depth can play a role in reducing the grinding force. By improving the grinding parameters, the stability of quartz plate grinding based on adhesive technology is verified. It is found that adhesive is a more reliable clamping method, which ensures the processing quality of quartz plate and improves the working efficiency.

Blocking uncertain mispriming errors of PCR

The polymerase chain reaction (PCR) plays a central role in genetic engineering and is routinely used in various applications, from biological and medical research to the diagnosis of viral infections. PCR is an extremely sensitive method for detecting target DNA sequences, but it is substantially error prone. In particular, the mishybridization of primers to contaminating sequences can result in false positives for virus tests. The blocker method, also called the clamping method, has been developed to suppress mishybridization errors. However, its application is limited by the requirement that the contaminating template sequence be known in advance. Here, we demonstrate that a mixture of multiple blocker sequences effectively suppresses the amplification of contaminating sequences even in the presence of uncertainty. The blocking effect was characterized by a simple model validated by experiments. Furthermore, the modeling allowed us to minimize the errors by optimizing the blocker concentrations. The results highlighted an inherent robustness of the blocker method in that fine-tuning the blocker concentrations is not necessary. Our method extends the applicability of PCR and other hybridization-based techniques, including genome editing, RNA interference, and DNA nanotechnology, by improving their fidelity.

Abstract P427: Novel SNVs of NBCe1, D405E and I803M mutants, reduced cell-surface expression and transport activity.

Introduction: The electrogenic Na + /HCO 3 - cotransporter NBCe1 is mainly expressed in proximal renal tubule, and regulate pH homeostasis and plasma volume. NBCe1 homozygous mutation causes many symptoms, including severe hypotension, proximal renal tubular acidosis (RTA), and extrarenal phenotype (migraine, mental retardation, mineral bone disorder and ocular abnormalities). Hypothesis: Undetermined single nucleotide variants (SNVs) in NBCe1 will be crucial role of sodium and bicarbonate transport. Methods: We identified the missense mutations (D405E and I803M) in NBCe1 variant A (kidney type) from the NCBI database. We conducted a comparative analysis of cellular localization and cell protein expression using confocal microscopy and western blotting. Furthermore, we performed functional analysis in D405E and I803M SNVs using two-electrode voltage clamp method. Results: Immunofluorescence analysis with confocal microscopy revealed that the D405E and I803M variants were present predominantly in the cell-surface in HEK293 cells. Western blotting in HEK293 cells confirmed that the D405E and I803M variants were significantly reduced protein expression level (25% in D405E and 57% in I803M) compared with WT, respectively. Moreover, electrophysiological analysis revealed that D405E and I803M variants were significantly reduced transport activity. These consisting data suggest that cell-expression level and transport activity are comparable. Conclusion: These data illustrate the diverse physiological consequences of distinct SNVs and underscore the importance of functional characterization in membrane transport proteins.

How i do it: individualized bypass strategy with tentative clamping method.

Cerebral Revascularization (CR) remained an indispensable arm in the neurosurgical arsenal, especially managing symptomatic hemisphere with misery perfusion (SHMP). We described an a mid-aged gentleman diagnosed with progressive middle cerebral steno-occlusion following carotid endarterectomy by employing individualized arterial reconstruction with tentative clamping method (TCM) under supervision of intraoperative monitoring. An operative video was also accompanied to demonstrate further details. The optimal treatment strategy for SHMP should be tailored by individuals. The risk of postoperative adverse sequel can be minimized and improved neuro-cognitive status was accomplished with an aid of TCM for such prophylactic procedure. NA.

The Ubiquitin Ligase Adaptor NDFIP1 Interacts with TRESK and Negatively Regulates the Background K+ Current.

The TRESK (K2P18.1, KCNK18) background potassium channel is expressed in primary sensory neurons and has been reported to contribute to the regulation of pain sensations. In the present study, we examined the interaction of TRESK with NDFIP1 (Nedd4 family-interacting protein 1) in the Xenopus oocyte expression system by two-electrode voltage clamp and biochemical methods. We showed that the coexpression of NDFIP1 abolished the TRESK current under the condition where the other K+ channels were not affected. Mutations in the three PPxY motifs of NDFIP1, which are responsible for the interaction with the Nedd4 ubiquitin ligase, prevented a reduction in the TRESK current. Furthermore, the overexpression of a dominant-negative Nedd4 construct in the oocytes coexpressing TRESK with NDFIP1 partially reversed the down-modulating effect of the adaptor protein on the K+ current. The biochemical data were also consistent with the functional results. An interaction between epitope-tagged versions of TRESK and NDFIP1 was verified by co-immunoprecipitation experiments. The coexpression of NDFIP1 with TRESK induced the ubiquitination of the channel protein. Altogether, the results suggest that TRESK is directly controlled by and highly sensitive to the activation of the NDFIP1-Nedd4 system. The NDFIP1-mediated reduction in the TRESK component may induce depolarization, increase excitability, and attenuate the calcium dependence of the membrane potential by reducing the calcineurin-activated fraction in the ensemble background K+ current.

An Enhanced Dynamic Collector Voltage and Current Clamping Method for Semiconductor in Electric Vehicles

The electric drive and the batteries are the two primary parts of an electric vehicle (EV). In order to increase the availability and dependability of the semiconductors used in traction converters, this research focuses on a new approach of semiconductor protection. The IGBT overshoot in voltage during a short circuit situation was successfully reduced by a newly created active voltage and current clamping circuit. This innovative method restricts IGBT’s collector-emitter voltage during the turn-off event. As soon as the collector-emitter voltage of the IGBT crosses a predetermined threshold, the IGBT is partially turned on. The IGBT is then kept operating linearly, minimizing the rate at which the collector current falls and, consequently, and the collector-emitter over voltage. Simultaneously, during the short circuit, the current is monitored by a high precision hall-effect sensor allegro make IC, which detects over current and provides a fault output within 1µs. As a result of the combination of current and voltage monitoring, the likelihood of the IGBT failure is reduced drastically.

Complete autonomic blockade reveals nitric oxide contribution to blood pressure regulation in obese Black women

PurposeHypertension is one of the major causes of cardiovascular morbidity and mortality in the USA and disproportionately affects Black women. Endothelial-derived nitric oxide (eNO) substantially regulates blood pressure in humans, and impaired NO-mediated vasodilation has been reported in the Black population. Previous studies using an NO synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA) did not fully determine the NO contribution to blood pressure because of baroreflex buffering. Therefore, in the present study we used trimethaphan, a ganglionic blocker, to inhibit baroreflex buffering and study NO modulation of blood pressure in Black women during L-NMMA infusion.MethodsL-NMMA at doses of 250 μg/kg per minute was infused in combination with trimethaphan at doses of 4 mg/min to eliminate baroreflex mechanisms. Heart rate (HR) was obtained with continuous electrocardiogram monitoring, and continuous blood pressure was measured with the volume clamp method. The increase in systolic blood pressure (SBP) during both infusions was used to estimate the contribution of NO to blood pressure.ResultsTen Black (age range 30–50 years, body mass index [BMI] 30–45 kg/m2), and nine White women (age range 30–50 years, body mass index 30–45 kg/m2) were enrolled in this study. During autonomic blockade, there was no difference in the decrease in SBP between Black and White women (− 20 ± 16.45 vs. − 24 ± 15.49 mm Hg, respectively; P = 0.659). When autonomic blockade was combined with L-NMMA, Black women had a significant increase in SBP compared to White women (54 ± 13.62 vs. 39 ± 09.64 mm Hg, respectively; P = 0.022, respectively).ConclusionAutonomic blood pressure regulation was similar between Black and White women. However, NO contribution to blood pressure was significantly greater in Black women compared to White women.RegistrationClinicalTrials.gov: NCT01122407.

Nanoemulsification of epigallocatechin gallate for debitterization, antibrowning, and inhibition of intracellular lipid accumulation

This study addressed the instability of epigallocatechin gallate (EGCG), a green tea-derived polyphenol, by developing a robust EGCG oil-in-water nanoemulsion. The nanoemulsion comprised lecithin (dispersed phase), pectin (continuous phase), and gallic acid (antibrowning agent). Using a blend of phases via high-energy ultrasonication, we achieved an 88.9% encapsulation efficiency. The nanoemulsion's physical properties improved, yielding a small droplet size (diameter: 169.3 nm) and low polydispersity index (0.16). The nanoemulsion exhibited long-term stability, 82% DPPH radical scavenging activity and 63% browning prevention compared with EGCG. Upon expressing the human taste receptor TAS2R16 + GIRK1/4 in Xenopus oocytes, the nanoemulsion elicited a 50% decrease in bitterness compared with EGCG, as quantified by the oocytes' membrane potential using the two-electrode voltage clamp method. Treating 3T3-L1 cells with the nanoemulsion resulted in a 49% reduction in lipid accumulation and 58% enhancement of triglyceride degradation, as confirmed via Oil Red O staining and lipolysis studies, respectively. This study provides insights into establishing an effective emulsification system for EGCG, enhancing its role as a functional food ingredient.

Induction of long-term hyperexcitability by memory-related cAMP signaling in isolated nociceptor cell bodies.

Persistent hyperactivity of nociceptors is known to contribute significantly to long-lasting sensitization and ongoing pain in many clinical conditions. It is often assumed that nociceptor hyperactivity is mainly driven by continuing stimulation from inflammatory mediators. We have tested an additional possibility: that persistent increases in excitability promoting hyperactivity can be induced by a prototypical cellular signaling pathway long known to induce late-phase long-term potentiation (LTP) of synapses in brain regions involved in memory formation. This cAMP-PKA-CREB-gene transcription-protein synthesis pathway was tested using whole-cell current clamp methods on small dissociated sensory neurons (primarily nociceptors) from dorsal root ganglia (DRGs) excised from previously uninjured ("naïve") rats. Six-hour treatment with the specific Gαs-coupled 5-HT4 receptor agonist, prucalopride, or with the adenylyl cyclase activator, forskolin, induced long-term hyperexcitability (LTH) in DRG neurons that manifested 12-24 hours later as action potential (AP) discharge (ongoing activity, OA) during artificial depolarization to -45 mV, a membrane potential that is normally subthreshold for AP generation. Prucalopride treatment also induced significant long-lasting depolarization of resting membrane potential (from -69 to -66 mV), enhanced depolarizing spontaneous fluctuations (DSFs) of membrane potential, and indications of reduced AP threshold and rheobase. LTH was prevented by co-treatment of prucalopride with inhibitors of PKA, CREB, gene transcription, and protein synthesis. As in the induction of synaptic memory, many other cellular signals are likely to be involved. However, the discovery that this prototypical memory induction pathway can induce nociceptor LTH, along with reports that cAMP signaling and CREB activity in DRGs can induce hyperalgesic priming, suggest that early, temporary, cAMP-induced transcriptional and translational mechanisms can induce nociceptor LTH that might last for long periods. An interesting possibility is that these mechanisms can also be reactivated by re-exposure to inflammatory mediators such as serotonin during subsequent challenges to bodily integrity, "reconsolidating" the cellular memory and thereby extending the duration of persistent nociceptor hyperexcitability.

Induction of long-term hyperexcitability by memory-related cAMP signaling in isolated nociceptor cell bodies

Persistent hyperactivity of nociceptors is known to contribute significantly to long-lasting sensitization and ongoing pain in many clinical conditions. It is often assumed that nociceptor hyperactivity is mainly driven by continuing stimulation from inflammatory mediators. We have tested an additional possibility: that persistent increases in excitability promoting hyperactivity can be induced by a prototypical cellular signaling pathway long known to induce late-phase long-term potentiation (LTP) of synapses in brain regions involved in memory formation. This cAMP-PKA-CREB-gene transcription-protein synthesis pathway was tested using whole-cell current clamp methods on small dissociated sensory neurons (primarily nociceptors) from dorsal root ganglia (DRGs) excised from previously uninjured (“naïve”) male rats. Six-hour treatment with the specific Gαs-coupled 5-HT4 receptor agonist, prucalopride, or with the adenylyl cyclase activator forskolin induced long-term hyperexcitability (LTH) in DRG neurons that manifested 12–24 h later as action potential (AP) discharge (ongoing activity, OA) during artificial depolarization to −45 mV, a membrane potential that is normally subthreshold for AP generation. Prucalopride treatment also induced significant long-lasting depolarization of resting membrane potential (from −69 to −66 mV), enhanced depolarizing spontaneous fluctuations (DSFs) of membrane potential, and produced trends for reduced AP threshold and rheobase. LTH was prevented by co-treatment of prucalopride with inhibitors of PKA, CREB, gene transcription, or protein synthesis. As in the induction of synaptic memory, many other cellular signals are likely to be involved. However, the discovery that this prototypical memory induction pathway can induce nociceptor LTH, along with reports that cAMP signaling and CREB activity in DRGs can induce hyperalgesic priming, suggest that early, temporary, cAMP-induced transcriptional and translational mechanisms can induce nociceptor LTH that might last for long periods. The present results also raise the question of whether reactivation of primed signaling mechanisms by re-exposure to inflammatory mediators linked to cAMP synthesis during subsequent challenges to bodily integrity can “reconsolidate” nociceptor memory, extending the duration of persistent hyperexcitability.

Analysis of the role of Na<sub>v</sub>1.5 slow inactivation in the development of inherited cardiac pathology

Voltage-gated cardiac sodium channels Nav1.5 are responsible for the initiation and propagation of action potentials in cardiomyocytes. Dysfunction of Nav1.5 can be caused both by pathogenic variants in the SCN5A gene itself, which encodes Nav1.5, and by genetic variants in the genes of other proteins, regulating channel activity and trafficking. The change of different phases of the action potential is determined by the strict temporal organization of activation and inactivation of various ion channels. Transitions between channel functional states (for example, to slow inactivated state) can be influenced by various factors and proteins interacting with the channel. Despite the fact that the process of slow inactivation of the channel has been known for several decades, its role in the mechanism of development of hereditary heart pathology remains unclear. In this work, using the patch clamp method in whole-cell leads, we studied changes in the process of slow Nav1.5 inactivation under the influence of various mutations in structural genes (DSP-H1684R, LMNA-R249Q, FLNC-R1267Q, FLNC-V2264M) associated with a genetically determined myocardial pathology leading to dysfunction of cardiomyocytes. The study used a model of cardiomyocytes differentiated from induced pluripotent stem cells (СM-iPSCs). We have demonstrated an increase in slow inactivation in the model of CM-iPSCs obtained from patients with a phenotype of cardiomyopathy combined with ventricular arrhythmias. Thus, this work contributes to understanding the role of the slow inactivation process in the mechanism of the development of heart pathology.

Numerical Investigation of the Irreversible Behavior of GDL Under Cyclic Hygrothermal Loading

Performances of proton exchange membrane fuel cells (PEMFCs) is impacted by the physical properties of the gas diffusion layer (GDL). These properties, including thickness and porosity, are irreversibly modified by diverse processes, notably by the clamping of the PEMFC or the swelling of the membrane during cell operation. This can result in irreversible deformation of the GDL, with consequent impact on the performance and durability of the PEMFCs. This phenomenon, which is difficult to apprehend experimentally, is also challenging to investigate numerically. An elastoplastic law related to the irreversible strain of the GDL after compression is proposed in this study and implemented in a finite element model. Variations in GDL’s properties during humidity and temperature cycles are studied depending on PEMFC clamping methods using numerical simulations. The influences of processing conditions, i.e. the membrane electrode assembly hot pressing process, on GDLs properties are also investigated numerically. The results demonstrate the necessity to take into account the evolution of the mechanical properties of PEMFC components, with a significant influence of clamping process, life load and hot pressing process on the physical properties of the GDL as thickness, porosity, or intrusion in the gas channels.

The TREK-1 potassium channel is a potential pharmacological target for vasorelaxation in pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease in which chronic membrane potential (Em) depolarisation of the pulmonary arterial smooth muscle cells (PASMCs) causes calcium overload, a key pathological alteration. Under resting conditions, the negative Em is mainly set by two pore domain potassium (K2P) channels, of which the TASK-1 has been extensively investigated. Ion channel currents and membrane potential of primary cultured human(h) PASMCs were measured using the voltage- and current clamp methods. Intracellular [Ca2+] was monitored using fluorescent microscopy. Pulmonary BP and vascular tone measurements were also performed ex vivo using a rat PAH model. TREK-1 was the most abundantly expressed K2P in hPASMCs of healthy donors and idiopathic(I) PAH patients. Background K+-current was similar in hPASMCs for both groups and significantly enhanced by the TREK activator ML-335. In donor hPASMCs, siRNA silencing or pharmacological inhibition of TREK-1 caused depolarisation, reminiscent of the electrophysiological phenotype of idiopathic PAH. ML-335 hyperpolarised donor hPASMCs and normalised the Em of IPAH hPASMCs. A close link was found between TREK-1 activity and intracellular Ca2+-signalling using a channel activator, ML-335, and an inhibitor, spadin. In the rat, ML-335 relaxed isolated pre-constricted pulmonary arteries and significantly decreased pulmonary arterial pressure in the isolated perfused lung. These data suggest that TREK-1is a key factor in Em setting and Ca2+ homeostasis of hPASMC, and therefore, essential for maintenance of a low resting pulmonary vascular tone. Thus TREK-1 may represent a new therapeutic target for PAH.

Impact of quetiapine on ion channels and contractile dynamics in rat ventricular myocyte

Antipsychotic drugs often lead to adverse effects, including those related to the cardiovascular system. Of these, quetiapine is known to cause significant changes in the QT interval although the underlying mechanism remains mysterious, prompting us to examine its effects on cardiac electrophysiological properties. Therefore, we investigated the effect of quetiapine on contraction, action potential (AP), and the associated membrane currents such as L-type Ca2+ and K+ using the whole-cell patch clamp method to examine its impacts on isolated rat ventricular myocytes.Our results showed that (1) quetiapine reduces cell contractility in a concentration-dependent manner and (2) leads to a significant prolongation in the duration of AP in isolated ventricular myocytes. This effect was both concentration and frequency-dependent; (3) quetiapine significantly decreased the Ca2+, transient outward K+, and steady-state K+ currents. However, only high concentration of quetiapine (100 μM) could significantly change the activation and reactivation kinetics of L-type Ca2+ channels.This study demonstrates that QT extension induced by quetiapine is mainly associated with the prolongation of AP. Moreover, quetiapine caused a significant decrease in contractile force and excitability of ventricular myocytes by suppressing Ca2+ and K+ currents.

Current status and future perspectives of robotic liver surgery.

Robotic liver resection has been reported in case series since the early 2000s. The surgical robot is capable of precise operation using articulated forceps with seven degrees of freedom. The robot also eliminates tremors and provides a good surgical field with highly detailed 3D high-definition images. The clinical results demonstrating their usefulness have been increasing year by year. Initially, a shorter hospital stay was observed in comparison with open hepatectomy. Recent reports have also shown lower conversion and complication rates in comparison with laparoscopic hepatectomy. The clamp and crush method with bipolar forceps, sealing devices, ultrasonic shears, and the combined procedure of Cavitron ultrasonic surgical aspirator and robotic forceps as hybrid procedures have been reported as effective methods of parenchymal transection in robotic surgery. Theoretically, the advantages of the robotic platform allow for more complex liver resection around hilar structures and major blood vessels, as well as for vascular reconstruction or biliary reconstruction. The application of robotic liver surgery for hilar cholangiocarcinoma, living donor hepatectomy, and living donor liver transplantation has been reported. Robotic liver surgery is becoming more popular for certain indications; however, it is important to further evaluate its long-term surgical and oncological outcomes and costs in comparison with conventional laparoscopic and open liver surgery, based on accumulated experience.

Preparation, Characterization, and High-Temperature Anti-Seizing Application of CrAlN-Based Gradient Multilayer Coatings

High-temperature fasteners are metal parts of gas turbines and steam turbines, which work at high temperatures and under stress for a long time. However, the frequent seizures of fasteners bring great trouble to the normal maintenance of power plants. In this paper, three kinds of dense and controllable CrAlN-based gradient multilayer coatings were prepared on the samples and screws by arc ion plating (AIP) technology. The morphology, composition, structure, nano hardness, adhesion, residual stress, and room temperature tribological performance of the coating were investigated. To evaluate the high-temperature, anti-seizing performance, coated screws were heated to 700 °C for 140 h with a torque of 20 N·m. The results indicate that the CrN/CrAlN multilayer coating shows better comprehensive properties. The characterization of coated screws proved that the coating structures obtained on the screws were similar to the flat samples. However, the as-prepared coating on the screws showed different thickness variation rules, which was related to the clamping method, deposition distance, and screw shape. After a simulation service, the thread of the screw remained intact with similar structure and thinner thickness. The above results indicate that the high-temperature seize prevention of fasteners can be successfully achieved by preparing a CrAlN-based multilayer coating, which is suitable for fasteners with service temperatures below 700 °C.