Nylon Film Research Articles

Targeted Genome Mining Facilitates the Discovery of a Promiscuous, Hyperthermostable Amidase from Thermovenabulum Gondwanense with Notable Nylon-Degrading Capacity.

Plastics are ubiquitous in our ecosystems, and microplastic accumulation in the environment is an emerging global health concern. Since available recycling technologies are not economically competitive with primary plastic production, global use is expected to reach 1231 megatons by 2060, with 493 megatons leeching into the environment each year. To identify new nylon-recycling biotechnologies, targeted genome mining was used to identify thermostable enzymes capable of degrading polyamides. Here, we describe the characterization of a novel protein sourced from Thermovenabulum gondwanense: TvgC. TvgC is extremely stable, exhibiting a melting temperature of 93 °C and no detectable losses in hydrolytic activity after one week at 60 °C. While nylonases primarily process nylon-6, TvgC catalysed the degradation of both nylon-6 and nylon-6,6 films, which are considerably more difficult to degrade. Finally, conversion experiments demonstrate that TvgC achieves a 1.2 wt % conversion of nylon-6 film, comparable to that of the most highly engineered nylonases. This novel hyperthermostable protein represents an excellent starting point for future engineering of increasingly efficient nylonases.

Determination of the Effects of Silver Nano-Particle Packaging Materials on Storability of Tomatoes

ABSRTACT
 The need to extend the shelf life of tomatoes has arisen due to the issue of post-harvest losses. This has prompted an exploration into active packaging materials. This study aimed to evaluate the effect of silver nanoparticle packaging material on tomatoes. Freshly cleaned tomatoes were stored at room temperature using two types of packaging materials, namely Styrofoam and High-Density Plastic (HDP). These packaging materials were then either covered with nylon film infused with silver nanoparticles or with regular nylon film. The tomatoes were left in storage for a period of 9 days, during which changes in fruit mass, moisture content, firmness, and the number of damaged tomatoes were carefully assessed. After 9 days, the weight of tomatoes infused with nanoparticles is 142g to 96g compared to the normal condition of 150g to 40g for high-density plastic (HDP) and 166g to 86g compared to the normal condition of 114g to 64g for Styrofoam. Overall, the results of the study demonstrated that post-harvest preservation of tomatoes using the investigated techniques of Silver Nanoparticle under two packaging materials extended days of firmness and reduced mold concentration count by 50%, thereby reducing the number of losses by 65-70%. The results obtained provide highly useful information in the field of post-harvest storage and preservation.
 Keywords: silver nanoparticles, Styrofoam, high-density plastic, tomatoes, preservation.

Modular Design of Multistable Pneumatic Structures from a Flat Pattern of Air Pouches

We introduce a novel family of structures that can be inflated from a plane to form a three-dimensional surface using articulated straight pouches with inextensible membranes. Specifically, we propose a modular design using a quadrangle surrounded by four slender pouches, whose inflation causes the surface to form a saddle shape. Then we show a fabrication method using heated nylon films with heat adhesives separated by paper mask patterns inside. We first show a geometric model to explain and predict the out-of-plane deformation and the bi-stability effect inherited in this structure. Through a geometric analysis and an elastic simulation of a pouch, we show that lowering the width-length ratio of pouches reduces the imperfection of shapes. We further propose a method for controlling the height of saddles using concentric patterns. We then extend structural modules into multiple-grid systems and identify the multistable behaviors of the overall structure.

Modelling the respiration rate of dabai fruit (Canarium odontophyllum Miq.) stored in different packaging films

Dabai (Canarium odontophyllum Miq.) is a highly nutritious fruit that has a huge potential to be marketed both locally and globally. However, the lack of promotion leads to an oversupply during peak season, thus reducing its market price. Proper handling and packaging are therefore necessary to maintain the quality and extend the shelf life of dabai. In the present work, nylon film with an oxygen transmission rate (OTR) of 55 cc/m2/day and water vapour transmission rate (WVTR) of 334 g/m2/day; polyethylene terephthalate (PET) film with an OTR of 90 cc/m2/day and WVTR of 35 g/m2/day; and low-density polyethylene (LDPE) film with an OTR of 8000 cc/m2/day and WVTR of 200 g/m2/day were used to pack dabai and stored at 5°C for 14 d. All films had a dimension of 200 × 300 mm, and a thickness of 0.01 μm. It was found that dabai maintained its hue angle (h°) values within the dark purple region (299.73° to 338.64°) and its lightness (L*) values throughout storage. However, the colour intensity (chroma) significantly changed (p < 0.05) between different films throughout storage (p < 0.05). The control sample had the most significant decrease in firmness and weight (p < 0.05) between day 0 and 14, followed by the samples stored in PET, LDPE, and nylon. Whereas the samples in LDPE demonstrated the lowest respiration rate as compared to nylon and PET. The uncompetitive Michaelis-Menten equation model was used to model the respiration rate of dabai. Results showed that all films obtained good fit (R2 of near to 1). Additionally, the mean relative percentage (E%) was less than 10%, thus indicating that the data were suitable for real-time application.

Effect of organic and synthetic mulches on some morpho-physiological and yield parameters of ‘Zard’ olive cultivar subjected to three irrigation levels in field conditions

Olive is one of the most important crops in arid and semi-arid areas. Prolonged water stress in these regions may adversely affect olive plant quality and productivity of fruits. To address the mitigation of unfavorable consequences of drought stress, the use of water-retaining mulches can be a beneficial solution. To achieve this purpose, the responses of olive cultivar ‘Zard’ as affected by mulch amendment [olive pomace, animal manure, nylon film, superabsorbent and control (without mulch)] and irrigation level (100 %ET as a normal condition and both 75 %ET and 50 %ET to simulate moderate and severe drought stress, respectively) were assayed. As a result, drought stress significantly retarded growth parameters, but fruit dry matter accumulation indicated the opposite behavior. Chlorophyll a + b, calcium, potassium, relative water content, and fruit yield also represented a declining tendency in severity-dependent behavior and conversely, sodium, antioxidant enzyme activity (catalase and peroxidase), oxidative markers, pulp/pit ratio, osmolytes (proline and total carbohydrates), and phenolic content increased in olive trees exposed to drought stress. Animal manure and especially olive pomace as organic mulches notably exhibited pragmatic influences on morpho-physiological as well as yield traits and improved pomological characteristics, regardless of tree water status. It was concluded that mulches used as water retaining agents, especially olive pomace and animal manure, can be effectively used to promote drought tolerance, growth and yield of olive trees growing in water deficit conditions. In general, using natural mulches is a good way to overcome drought stress.

A drum structure triboelectric nanogenerator based on PS/MXene for football training monitoring

Recently, flexible multifunctional sensors have attracted widespread attention from around the world. Here, we propose a novel PS/MXene-based triboelectric nanogenerator (PM-TENG), which has a drum structure design. Through comparative experiments, the optimal ratio of polystyrene (PS) materials was explored. The PS film and nylon film form the triboelectric materials, and copper foil acts as the conducive electrode. From the results, the open-circuit voltage (Voc) and short-circuit current (Isc) of the PM-TENG based on 35 mg/ml content of PS can reach 141 V and 5.9 µA, respectively. In addition, when the resistance value of the external load is 50 MΩ, the PM-TENG exhibits a maximum output power of 123 µW. Due to its excellent flexibility, the PM-TENG can be installed on the shoulders, neck, wrist, elbow, knee, and ankle to achieve all-round motion monitoring of football players. This research can promote the application of TENG sensors in the football monitoring field.

Fabrication and feasibility study of polymer-based triboelectric nanogenerator towards blue energy harvesting

The goal of this study was to investigate a new aspect of polymeric film modification used in triboelectric nanogenerators (TENGs). TENGs were fabricated using fluorinated ethylene propylene (FEP) and chemically etched nylon films. The FTIR spectra confirmed the retained polymeric nature of the modified nylon films, and the AFM results showed an improvement in the roughness of the film surfaces after chemical treatment. The as-fabricated floatable TENGs delivered an open-circuit voltage of 12 V when subjected to an external force, and could glow a few light-emitting diodes (LEDs) with water waves. The findings of this study will open new prospects for the future development and optimization of polymer-based TENGs for blue energy harvesting.

A Wireless Intelligent Motion Correction System for Skating Monitoring Based on a Triboelectric Nanogenerator

Smart sport and big data have become inextricably linked with new technologies and devices to monitor sport-related information in real time. In this paper, a lightweight, portable and self-powered triboelectric nanogenerator (LPS-TENG) has been developed to monitor the frequency and force of skaters’ pedaling. Friction layers are formed of polytetrafluoroethylene (PTFE) and nylon films. Based on the triboelectric effect, LPS-TENG does not require an external power supply, and it can be used to monitor biomechanical motion independently. Under the conditions of 1 Hz and 17.19 N, the outputting voltage of LPS-TENG is stabilized at 14 V. Wireless data transmission is achieved with the help of the LPS-TENG and AD module. Visual feedback is provided by the upper computer system in the process of processing data. The wireless intelligent motion correction system is composed of an LPS-TENG, an AD module and a back-end computer. It can clearly analyze the changes between different frequencies and forces during skating. Results showed that the signal of tester’s high-frequency and great-force motion, was transmitted to the computer, and its feedback was given after analysis and processing successfully. The system may help coaches develop training methods, means and tactics to increase athletes’ performance and competitive level in athletic sport. The purpose of this study is to provide new ideas for monitoring skaters’ sport techniques, promote the use of force sensors in the monitoring of sport and develop intelligent assistant training systems.

A Triboelectric Nanogenerator Based on a Pendulum-Plate Wave Energy Converter

Abstract Ocean waves are a promising source of renewable energy, but harvesting this irregular low-frequency energy is challenging due to technological limitations. In this paper, a pendulum plate-based triboelectric nanogenerator (PP-TENG) is proposed. The PP-TENG absorbs wave energy through the pendulum plate installed at the bottom of the device, which generates a swing effect. This drives the motion of the upper TENG power generation unit and generates a charge transfer on the surface of a film of polymer PTFE and nylon, materials which are very sensitive to the low-frequency wave environment. The PP-TENG was tested after building a semi-physical simulation test platform. When the polymer materials were PTFE with a thickness of 0.01 mm and nylon with a thickness of 0.02 mm, 33 commercial LED lamps could be lit simultaneously. Moreover, under short-circuit conditions, the current reached 2.45 μA, and under open-circuit conditions, the voltage reached 212 V. When the PP-TENG was connected in series with a resistor with a resistance of 3 × 105 Ω, its maximum peak power density reached 6.74 mW/m2. It can be concluded that the PP-TENG is characterised by low fabrication costs and excellent energy conversion efficiency. The combination of a pendulum wave energy converter with a TENG shows great output performance. This research lays a solid foundation for practical applications of the proposed structure in the future.

Formation of Shewanella putrefaciens biofilms on nylon film and effects on putrefaction of large yellow croaker

Biofilms formed on food contact surfaces cause significant economic loss in the food sector and pose a serious public health concern. In this study, the formation of Shewanella putrefaciens (S. putrefaciens) biofilms on nylon film at 30°C and 4°C was investigated. Results indicated that more biofilms were formed at 4°C, which peaked after 60 h incubation. The protease activity in biofilms was significantly higher than that in the corresponding plankton culture, and it was closely related to the development stage of biofilms. Besides, S. putrefaciens biofilms formed on nylon film in large yellow croaker juice and fresh cubes at 4°C were also investigated, and SDS-PAGE patterns demonstrated that S. putrefaciens biofilms showed a higher capacity to decompose proteins than planktonic bacteria. This work provided insight into the development of biofilms on nylon film, allowing for further controlling S. putrefaciens biofilms in food packages in the future. Practical applications Flexible plastic packaging with nylon film is widely used for packaging perishable food products including marine fish, smoked fish, processed meats such as sausage and bacon, dairy products, and prepared ready meals due to its various advantages of thermoformability, mechanical strength and toughness, transparency, and oxygen barrier properties. However, the formation of biofilms on the packaging surfaces can cause significant economic loss in the food industry and pose serious public health concerns. This study compared the formation of Shewanella putrefaciens biofilms on nylon film at 30°C and 4°C, and the results can provide further insight into the development of biofilms on nylon film, allowing for better control of S. putrefaciens biofilms in food packages, which is thus very beneficial for the food industry and consumers to ensure food safety.

Effect of Packaging Materials on Antifogging Film Properties and Quality of Oyster Mushrooms at Different Storage Temperatures

Mushroom is highly perishable and easily damaged within a day after harvesting due to their high respiration rate which leads to the release of water vapour. The most effective way to preserve fresh mushrooms is by packaging. However, excessive water vapour inside the packaging can cause condensation or fog and subsequently, lead to product damage. Hence, appropriate material for packaging mushrooms is important to maintain the quality and prolong the shelf-life. The main objective of this study is to compare the effect of different packaging material types on the fogging effect. The studied materials are low-density polyethylene (LDPE), polypropylene (PP), nylon, and gelatin-based film. Based on the market survey prior to the study, it showed that the most plastic material used in the market is polypropylene (PP) compared to other materials. The experimental study then proceeded by comparing the different types of materials used for the packaging of mushrooms. Samples of 20 g mushrooms were filled in a cup covered with four different types of films and stored at three different storage temperatures (5 °C, 10 °C, 30 °C) for 7 days. It was observed that the gelatin-based film showed good antifogging behaviour when compared to other films. Additionally, the mushrooms showed high weight loss and severe browning for all types of packaging materials after 7 days of storage at high temperatures (30 °C). In conclusion, the gelatin-based film has revealed excellent water-adsorbing with antifogging behaviour to maintain the quality and shelf life of mushrooms at low temperatures for storage and distribution.

A 3D Printing Triboelectric Sensor for Gait Analysis and Virtual Control Based on Human–Computer Interaction and the Internet of Things

Gait is the information that can reflect the state index of the human body, and at the same time, the leg is the organ with the maximum output power of the human body. Effective collection of maximum mechanical power output and gait information can play an important role in sustainable energy acquisition and human health monitoring. In this paper, a 3D printing triboelectric nanogenerator (3D printed TENG) is fabricated by 3D printing technology, it is composited of Poly tetra fluoroethylene (PTFE) film, Nylon film, and 3D printing substrate. Based on the principle of friction electrification and electrostatic induction, it can be used as the equipment for human sustainable mechanical energy collection and gait monitoring. In order to solve the problems of energy collection, gait monitoring, and immersion experience, we conducted the following experiments. Firstly, the problem of sustainable energy recovery and reuse of the human body was solved. Three-dimensionally printed TENG was used to collect human mechanical energy and convert it into electric energy. The capacitor of 2 μF can be charged to 1.92 V in 20 s. Therefore, 3D printed TENG can be used as a miniature sustainable power supply for microelectronic devices. Then, the gait monitoring software is used to monitor human gait, including the number of steps, the frequency of steps, and the establishment of a personal gait password. This gait password can only identify a specific individual through machine learning. Through remote wireless transmission means, remote real-time information monitoring can be achieved. Finally, we use the Internet of Things to control virtual games through electrical signals and achieve the effect of human–computer interaction. The peak search algorithm is mainly used to detect the extreme points whose amplitude is greater than a certain threshold and the distance is more than 0.1 s. Therefore, this study proposed a 3D printed TENG method to collect human mechanical energy, monitor gait information, and then conduct human–computer interaction, which opened up a multi-dimensional channel for human energy and information interaction.

Influence of characteristic parameters on the tribological properties of vein-bionic textured cylindrical roller thrust bearings

In this research, three types of vein-bionic texture patterns inspired by five kinds of leaves (Forsythia, Clausena lansium, Ash, Pipal, and Apricot) were designed and fabricated on the raceways of the shaft washers of cylindrical roller thrust bearings (CRTBs) through a fiber laser marking system. A vertical universal wear test rig was used to obtain the coefficient of friction (COF) of bearings under starved lubrication, with a customized tribo-pair. The wear losses of the shaft washers and the worn surfaces were characterized. The influence of different veins (chief, primary, secondary) and vein-structure characteristics (pattern symmetry, number of veins) on the tribological behavior of vein-bionic textured CRTBs is investigated and discussed. The results show that the original vein-bionic (V) pattern inspired by the Ash has the best friction-reducing performance, while the texture with the no-chief vein (NC) obtained by Clausena lansium has the best wear resistance. The chief vein mainly contributes to the low friction by enhancing the secondary lubrication effect and facilitating the formation of a protective nylon film. A reasonable mechanism for improving the tribological properties of resulting textures is proposed.

Gait analysis by using electric signals from a triboelectric nanogenerator

Gait monitoring is one of important healthcare methods. Gait disorders can be analysed by gait monitoring and related diseases can be further diagnosed. Daily living gait data are obtained by sensors such as accelerometers. In this study, A triboelectric nanogenerator (TENG) which is a well-known energy harvester was assembled into the accelerometer by attaching a drop-cast thin silicone rubber film to the movable mass and a thin nylon film to the fixed base of the accelerometer. Electrical outputs from this prepared TENG based gait monitoring device (TENGAIT) were investigated as the up-and-down reciprocating movement was applied by a Scotch yoke device in which the frequency of the up-and-down movement was controlled by an electric motor. The TENGAIT showed subsequent increase in voltage peaks from 2.5 V to 4 V and in current from 0.3 μA to 0.5 μA as the up-and-down frequency increased from 1 Hz to 5 Hz. The TENGAIT was then installed on a foot to obtain information about gait during walking on the spot in real-time. The voltage and the current showed 2.4 and 2.6 times increase, respectively, comparing the normal walking speed (0.8 Hz) to the fast walking speed (2 Hz). The light running could be distinguished from the fast walking by comparing gait speed and amplitude. And a gait cycle which includes the toe-touch, the heel-touch, the heel-off and the toe-off could be successfully analysed through changes in the shape of the current graph.

Analysis of Deterioration Mechanism of Al-Pouch Film Used As Packaging Materials for Lithium Ion Batteries

Generally, lithium ion batteries (LIBs) can be divided into three different types: cylindrical, prismatic, and pouch-type LiBs with regard to the packaging form. Contrary to cylindrical or prismatic type batteries, pouch-type battery uses a pouch as an exterior material to protect inside of the cell from external influences, and have a metal lead-taps to receive and deliver electricity from external source. To safeguard the inside of the lithium ion battery, the pouch must have high resistance to gas and moisture permeability and excellent corrosion resistance to electrolytes.However, Al-pouch can be prone to contamination from electrolyte containing lithium salt during the electrolyte injection process, a key part of their manufacturing process. This electrolyte contamination can be fatal to the long-term reliability or durability of pouch-type LiBs. In this study, we investigate deterioration behavior of aluminium pouch film due to the electrolyte contamination. In order to clarify deterioration mechanism of Al-pouch film, we prepared exposure test of Al-pouch film and dummy cell samples which were stained by electrolyte droplet (LiPF6 in EC:EMC=1:2 (v/v) + 2 % VC). The change of micro-structure of the samples was tracked during 20 weeks by storing them under accelerated test conditions (RH 95 %, 60 ℃). As a result, we find out severe defect of the samples of Al-pouch film by damage to outermost nylon film and aluminium layer, and confirmed the effects on the battery after the defects occurred.To understand such phenomena, the micro-defect of Al-pouch films was observed by characterization techniques (XRD, FT-IR, SEM, EDX). We demonstrate that outermost layer of nylon film is damaged when it reacts with an electrolyte containing LiPF6 salt such as decreasing crystallinity, surface crazing, forming microdefects. The degradation of nylon film leads to severe surface cracking, followed by nylon locally peeling off from the Al-pouch. Peeling of the nylon film causes to expose the underlying thin aluminum film that constitute the middle layer of Al-pouch. Once partially exposed to the atmosphere, severe pitting corrosion of the aluminum film occurs due to atmospheric moisture and acids produced by LiPF6. Finally, a large amount of moisture to easily penetrate pouch-type LiBs through these corroded pits, showing the detrimental effects of electrolyte contamination on pouch-type LiBs’ long-term durability and reliability. Figure 1

Research on the Friction and Wear Properties of Dents Textured Rolling Element Bearings under Dry Wear

To explore the effect of dents on the tribological behavior of the “washers-cage-rollers” system of rolling element bearings (REBs), the friction and wear properties of dents textured thrust cylindrical roller bearings (81107TN) with different diameters of dents (DAOD, 200, 250, 300 μm), depth of dents (DPOD, 4, 8, 12 μm) as well as circumferential interval angle (CFIA, 1.5°, 2.0°, 2.5°) were researched under dry wear. The surface stresses of REBs and the influence mechanism of dents were also compared and discussed. The results show that: due to the nylon film formed and left on the raceways, the coefficients of friction (COFs) of dents textured bearings are all higher than the average COF of smooth ones, while their wear losses may become higher or lower, depending on the combination of pattern parameters. The influence of the DPOD on the tribological performance of textured bearings is more significant than that of the DAOD. The results show that, when the DAOD and DPOD are 250 and 8 μm, respectively, compared with the smooth ones, the mass losses of bearings can be reduced by up to 49.22% under dry wear, which would be an important reference for the optimal design of the “washers-cage-rollers” system of REBs.

A self-powered triboelectric pressure sensor for basketball training monitoring

Triboelectric nanogenerators (TENGs) have emerged as a potential energy harvester and for self-powered motion monitoring. Recently, more and more work is focused on expanding TENG applications. Here, we designed a flexible multifunctional silica gel-based triboelectric nanogenerator (S-TENG) as the self-powered pressure sensor. In our design, the triboelectric layers consist of the silica gel film with a convex array and nylon film. The results showed that the S-TENG-based pressure sensor has good linearity and detection range. Furthermore, the S-TENG-based pressure sensor can be used for basketball training monitoring.

Highly durable direct-current power generation in polarity-controlled and soft-triggered rotational triboelectric nanogenerator

While the sliding-mode triboelectric nanogenerators (TENGs) have demonstrated one of the most efficient rotational energy harvesting devices, alternating-current (AC) generation and wear-off have been a long-standing bottleneck for practical applications. Here, we developed a polarity-controlled and soft-triggered (P-S) TENG for highly efficient and durable direct-current (DC) power generation. The P-S TENG consists of polytetrafluoroethylene (PTFE), nylon, and Cu films for triboelectrification, as well as another Cu film for charge-delivering electrode. The PTFE and nylon films were alternately attached to the outer acrylic cylinder, and four-segmented Cu films were attached to the inner acrylic cylinder. The P-S TENG generated a power-density of 0.32 mW/cm2, which was 4-fold and 32-fold larger than that of paired alternate and single polarity TENG, respectively. Remarkably, the DC output of P-S TENG remained nearly constant, despite 372,000 rotations, which sharply contrasted with the substantial power decrease (47%) in hard-triggered TENG. This work provides an important advancement in a rotational TENG with high DC power generation and long-term durability.

A buckling-sheet ring oscillator for electronics-free, multimodal locomotion.

Locomotion of soft robots typically relies on control of multiple inflatable actuators by electronic computers and hard valves. Soft pneumatic oscillators can reduce the demand on controllers by generating complex movements required for locomotion from a single, constant input pressure, but either have been constrained to low rates of flow of air or have required complex fabrication processes. Here, we describe a pneumatic oscillator fabricated from flexible, but inextensible, sheets that provides high rates of airflow for practical locomotion by combining three instabilities: out-of-plane buckling of the sheets, kinking of tubing attached to the sheets, and a system-level instability resulting from connection of an odd number of pneumatic inverters made from these sheets in a loop. This device, which we call a "buckling-sheet ring oscillator" (BRO), directly generates movement from its own interaction with its surroundings and consists only of readily available materials assembled in a simple process-specifically, stacking acetate sheets, nylon film, and double-sided tape, and attaching an elastomeric tube. A device incorporating a BRO is capable of both translational and rotational motion over varied terrain (even without a tether) and can climb upward against gravity and downward against the buoyant force encountered under water.

Multi-cylinder-based hybridized electromagnetic-triboelectric nanogenerator harvesting multiple fluid energy for self-powered pipeline leakage monitoring and anticorrosion protection

With the continuous development of human society and urban construction, exploring sustainable power sources of monitor and protection systems for city’s infrastructure is becoming more and more urgent. Scavenging ambient fluid flow energy to efficiently and conveniently power electric devices has potential applications for pipeline systems, especially in remote areas. Here, a multi-cylinder-based hybridized electromagnetic-triboelectric nanogenerator (MCNG) is reported to harvest two types of fluid energy at the same time to double the working frequency of the hybrid NG. The introduction of Nylon film effectively improved the durability and output performance. And the structure to transmit external mechanical through magnetic coupling is easy to packaging and assembly, which provides a stable inner environment. Moreover, the hybrid nanogenerator was demonstrated to effectively harvest energy from wind and water flow to power 1075 LEDs and a temperature sensor. Furthermore, a self-powered wireless pipeline leakage monitoring system and a self-powered cathodic protection system based on the MCNG are developed and illustrated. This work provides a prospective strategy for hybrid nanogenerator to improve working frequency and output stability for practical applications.