Operating Temperature Limit Research Articles

Synergistic effects of anionic surfactant doping on dielectric and electro-optical properties of nematic liquid crystals by cyano-ionic interactions

Modern research has long focused on controlling and optimizing the dielectric, electro-optical and optical attributes of liquid crystals (LCs) to increase their technological value. Numerous approaches have been investigated for this reason in an effort to overcome various issues such as high response time, high driving voltage requirements, low dielectric anisotropy and limited operating temperature range, etc. The strategy utilizing binary/multicomponent systems is the most investigated and seems to have the most potential out of all the other techniques. In keeping with the same subject, the influence of anionic surfactant on the dielectric, electro-optical, and optical properties of nematic LC (NLC) has been examined. Precisely, dodecane-1-sulfonic acid sodium salt (SDS) which is an anionic surfactant was dispersed in a room temperature NLC E7 at various concentrations. Our findings reveal a significant alteration in the electro-optical behavior resulting from the introduction of an anionic surfactant, extending well beyond the instance of electrode polarization, albeit with a detrimental impact on performance within the low-frequency range as a result of increased ionic contribution. The main findings of this study include a 17.5%% increase in dielectric anisotropy, an appreciable reduction of about 30%% in threshold voltage and rotational viscosity, and approximately 64% reduction in response time in the host NLC due to the addition of anionic salt in it. A significant photoluminescence quenching of about 64%% is observed after dispersion of 3.0% by weight anionic surfactant in E7. These findings offer potential pathways for the development of future technologies in various domains, including photonic devices, biological imaging, light-emitting diodes (LEDs), and luminescent markers.

Enhanced acetone detection performance of mechanically-mixed WO3:ZnO composites

In recent years, the potential use of mixed metal oxide WO3:ZnO is widely sought in photocatalytic application due to its excellent electrical and optical properties, but is less explored for chemiresistive sensor. The heterojunction effect in WO3:ZnO is of particular interest to eradicate common issues suffered by the pristine metal oxide sensors, such as limited sensitivity, poor selectivity, and high operating temperature. In addition, the acetone detection study based on heterostructured WO3:ZnO is quite limited. Herein, we demonstrate that the mechanically-mixed WO3:ZnO sensor exhibits comparable reducing gas sensing performance as other doped WO3:ZnO and relative improvement compared with the undoped composites, without the need of catalyst. In this work, WO3:ZnO thin-film based chemiresistive sensors were fabricated through straightforward methods comprising mechanical mixing and drop casting of sensor materials onto gold interdigitated alumina substrates. Structural and morphological properties of the prepared WO3, ZnO, and WO3:ZnO composites were examined through the X-ray diffraction (XRD), Raman spectroscopy, photoluminescence spectroscopy (PL), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) analyses, respectively. Sensor performance parameters including operating temperature and response were determined. The sensing properties of WO3:ZnO composites with different weight compositions (1:1, 1:2, and 1:3) were evaluated against the pristine ZnO and WO3. The weight ratio of 1:2 was the optimal composition for the WO3:ZnO composite to achieve the highest sensor response of 53.8 % towards 300 ppm acetone at 200 ºC compared to the pristine ZnO with a response of 23.5 %. The WO3:ZnO (1:2) thin film displayed granular morphology with uniform particle dispersion and porosity, enhancing the gas diffusion. The WO3:ZnO (1:2) thin-film composite sensor exhibited improved sensing performance and good repeatability towards acetone compared with that of ZnO and WO3. The enhanced response to acetone was possibly contributed by the development of n-n heterojunctions, porous morphology, and surface defects in the WO3:ZnO composite. The underlying sensing mechanism of WO3:ZnO composite is also discussed extensively with the aid of energy band diagrams. This study presents a foundation for future development of cost-effective acetone sensors through mechanical mixing with great potential for practical and scalable implementation in various industries.

An in situ exsolution strategy to prepare metallic Sn modified SnO2 with oxygen vacancies for ppb-level NO2 detection

The practical applications of SnO2 materials for NO2 detection in the field of indoor air quality monitoring are strongly plagued by low sensitivity toward ppb-level NO2. Herein, an in situ exsolution strategy was developed to prepare Sn-containing materials with abundant oxygen vacancy defects and Sn/SnO2 heterojunctions (designated as Sn/SnO2-x), which were obtained by annealing mixture of commercial SnO2 and NaBH4 in Ar atmosphere. Compared to commercial SnO2, the optimal Sn/SnO2-x-3 displays the obvious advantages of low operating temperature (110 °C), high sensitivity (response value of 4.65 toward 80 ppb NO2), and low limit of detection (10 ppb NO2 with response value of 1.17). The improvement of NO2 sensing performances is attributed to the synergistic effect of introducing oxygen vacancy defects and constructing Sn/SnO2 heterojunctions. Theoretically, the former leads to increasing the active sites for adsorption of NO2 and the latter reduces the band gap for improvement of carrier concentration. Additionally, this NO2 sensor shows excellent sensing performances for monitoring NO2 concentration in simulated indoor environment. This work not only provides an effective and large-scale approach to prepare novel sensing materials from commercial metal oxides by exsolution method, but also opens the way to fabricate high-performance gas sensors for detection of NO2 with low concentrations.

A filling rig for liquid and gas working fluids for two-phase thermal management systems

Two-phase cooling devices are used to remove and dissipate heat from high power-density electronic systems to maintain them within their operating temperature limits. The manufacture of these devices, such as heat pipes, thermosyphons or vapour chambers, involves firstly removing any internal air or non-condensable gases before charging with the required volume of working fluid. This paper presents detailed designs and operating instructions for a single bench-top station for use in a laboratory environment for the vacuum evacuation, degassing and charging of these devices. Two configurations allow for the filling of fluids which are either liquids or gases at standard temperature and pressure conditions. For liquids, the dispensed volume can be measured directly on an integrated burette, while the method of vapour transfer is used for gases.The hardware was demonstrated by filling multiple thermosyphon devices with a number of common working fluids used in two-phase systems, including water, acetone and ammonia. It was shown to deliver precise and repeatable filling volumes with average differences compared to target volumes of 1.7% and 10.5% for liquids and gases respectively. The design is intended to be highly customisable where its size can be modified to accommodate filling volume requirements for different applications.

High-temperature reverse osmosis and molecular separation with robust polyamide-ceramic membranes

Polyamide thin-film composite (TFC) membranes are widely used for reverse osmosis (RO), but most commercial RO membranes have a limited operating temperature of <45 °C. This has constrained the broader applications of RO in industries, where process and water feeds with high temperature >50 °C are common. In this study, robust polyamide-ceramic TFC membranes were developed for high-temperature RO (HT-RO). RO-type polyamide thin-film was successfully synthesized on the inner surface of ceramic tubular membranes via interfacial polymerization. The polyamide-ceramic membranes exhibited excellent thermal stability, maintaining high NaCl rejection (>98 %) and steady water permeability (∼5 LMH/bar) during HT-RO at 70 °C. The molecular weight cut-off (MWCO) of the membranes increased slightly from 90 to 140 Da at 70 °C, and the surface charge played an important role in maintaining the high salt rejection. Long-term stability tests showed that polyamide thin-films may undergo thermal hydrolysis at 80 °C. It was also found that polymeric substrates of flat-sheet RO membranes may experience serious compaction at high temperature, which could subsequently affect the performance and stability of the polyamide layer. The ceramic substrates provide strong support at high temperature, and the highly stable polyamide-ceramic membranes demonstrated huge potential for RO applications under more challenging conditions.

Experimental and Numerical Investigation of Macroencapsulated Phase Change Materials for Thermal Energy Storage.

Among the different types of phase change materials, paraffin is known to be the most widely used type due to its advantages. However, paraffin's low thermal conductivity, its limited operating temperature range, and leakage and stabilization problems are the main barriers to its use in applications. In this research, a thermal energy storage unit (TESU) was designed using a cylindrical macroencapsulation technique to minimize these problems. Experimental and numerical analyses of the storage unit using a tubular heat exchanger were carried out. The Ansys 18.2-Fluent software was used for the numerical analysis. Two types of paraffins with different thermophysical properties were used in the TESU, including both encapsulated and non-encapsulated forms, and their thermal energy storage performances were compared. The influence of the heat transfer fluid (HTF) inlet conditions on the charging performance (melting) was investigated. The findings demonstrated that the heat transfer rate is highly influenced by the HTF intake temperature. When the effect of paraffin encapsulation on heat transfer was examined, a significant decrease in the total melting time was observed as the heat transfer surface and thermal conductivity increased. Therefore, the energy stored simultaneously increased by 60.5% with the encapsulation of paraffin-1 (melting temperature range of 52.9-60.4 °C) and by 50.7% with the encapsulation of paraffin-2 (melting temperature range of 32.2-46.1 °C), thus increasing the charging rate.

Single-photon detection using large-scale high-temperature MgB2 sensors at 20 K

Ultra-fast single-photon detectors with high current density and operating temperature can benefit space and ground applications, including quantum optical communication systems, lightweight cryogenics for space crafts, and medical use. Here we demonstrate magnesium diboride (MgB2) thin-film superconducting microwires capable of single-photon detection at 1.55 μm optical wavelength. We used helium ions to alter the properties of MgB2, resulting in microwire-based detectors exhibiting single-photon sensitivity across a broad temperature range of up to 20 K, and detection efficiency saturation for 1 μm wide microwires at 3.7 K. Linearity of detection rate vs incident power was preserved up to at least 100 Mcps. Despite the large active area of up to 400 × 400 μm2, the reset time was found to be as low as ~ 1 ns. Our research provides possibilities for breaking the operating temperature limit and maximum single-pixel count rate, expanding the detector area, and raises inquiries about the fundamental mechanisms of single-photon detection in high-critical-temperature superconductors.

Application of advanced Wide-Temperature range and flame retardant “Leaf-Vein” Structured functionality composite Quasi-Solid-State electrolyte

Currently the advancement of lithium batteries have led to their widespread adoption in cutting-edge applications, with a heightened focus on their stability and safety in extreme environments. Traditional liquid electrolytes present challenges such as flammability, leakage, and limited operating temperature ranges, impeding the progress of electrochemical energy storage devices. Quasi-solid-state electrolytes(QSE) have emerged as a promising solution to overcome these limitations. Hydrogel electrolytes have garnered significant research attention due to their rapid ion conductivity, flexibility, functionality, low cost, and environmental compatibility. However, hydrogel electrolytes still face challenges such as narrow electrochemical window, low mechanical strength, and susceptibility to freezing. Herein, this study introduces a novel “leaf-vein” structured QSE, fabricated by combining a flexible hydrogel (UV in-situ curing) with a robust nanofiber network (electrospinning). The original QSE exhibits flame retardant (30 min non-flammability), broad electrochemical window (4.2 V), freeze resistance (- 60 °C) with 0.25 MPa, and self-healing capabilities. The assembled full battery demonstrates exceptional electrochemical stability at ultra-low temperatures. This distinctive structure of the QSE indicates novel insights and directions for the design and material selection of advanced electrolyte materials, enabling secure applications of electrochemical energy storage in specialized domains particularly deep space and polar exploration.

Enhanced dielectric reliability in the X9R‐type Bi1/2Na1/2TiO3‐CaZrO3 relaxor ferroelectric ceramics

AbstractHigh‐performance dielectric ceramic capacitors for automotive applications require high operation temperature, thermal stability, and reliability for dielectric ceramics. A broad composition search has been carried out to replace the existing BaTiO3‐based dielectrics having limited upper operating temperature due to the relatively low Curie temperature at around 120°C. However, most of the developed compositions are too complicated and compositionally sensitive, making them difficult to commercialize. This study introduces a dielectrically reliable ceramic system based on Bi1/2Na1/2TiO3 (BNT) with a wide operation temperature range simply by adding paraelectric CaZrO3 (CZ). At 15 mol% addition of CZ to BNT, the permittivity variation within ±15% from −55 to 280°C was achieved, which surpasses the EIA‐X9R standard. Moreover, the dielectric reliability was shown with low dielectric loss (tanδ &lt; 0.02) for the aforementioned temperature range and remarkable dielectric breakdown strength (∼260 kV/cm) at room temperature. Along with the proposal of a promising high‐performance dielectric material, structural analysis and dielectric behavior investigation as a function of CZ contents were presented.

A comparative study of thermo‐physical properties of different nanofluids for effective heat transfer leading to Li‐ion battery pack cooling

AbstractThe rapid advancement in Lithium‐ion battery technology has significantly boosted the electric vehicle market worldwide. These batteries are highly sought after by automobile manufacturers and researchers due to their exceptional energy storage and power capabilities. However, efficient working temperatures ranges from 15°C to 35°C, making it essential to implement battery cooling and heating methods to maintain optimal performance. This study primarily focuses on battery cooling. The automotive manufactures have focused on ethylene glycol, water and synthetic oils as commonly used coolants for keeping the lithium‐ion battery pack within working temperature limits. However, these fluids have lower heat conduction, leading to reduced heat transfer rates and diminished cooling performance. To address this issue, nano‐enhanced fluids, which are engineered fluids containing suspended nanospheres, have been explored. The heat transfer properties of conventional coolants are increased using nano‐enhanced fluids, thereby improving heat conduction and promoting efficient heat transfer within the battery. The study compares the temperature‐related characteristic of different nano‐enhanced fluids, including oxides of copper (CuO), titanium (TiO2), aluminum (Al2O3), silicon (SiO2), and zinc (ZnO), when added to base fluids such as synthetic oils, water and ethylene glycol. The importance to capacity of specific heat, conductivity of fluid thermally, fluid resistance to flow and fluid volumetric mass which are affected by changes in temperature limits are stressed upon. Depending on the specific application and test conditions, the effectiveness of one nano‐enhanced fluid may outperform the others. In conclusion, the thermo physical properties of nanofluids play a critical role in maintaining the battery pack temperature within operating temperature limits. The selections of nanofluids for particular battery thermal management system depends upon its arrangement along the battery pack and cell geometry. The cooling performance using nanofluids as coolant is 10% to 15% higher than the conventional used fluids. This nano‐enhanced fluid show great promise in enhancing the cooling capabilities of battery cooling systems, contributing to improved Lithium‐ion battery performance in electric vehicles.

Next Generation Fluorine-Free Proton Exchange Membranes for Electrochemical Energy Applications

Most commercially available proton exchange membrane (PEM)-based fuel cell and electrolyser systems currently employ perfluorinated sulfonic acid (PFSA)-based PEMs, e.g., Nafion. The use of these fluorinated polymers presents serious health and environmental concerns as their production, degradation, and disposal results in the release of hazardous perfluorinted compounds that have been shown to accumulate in the environment and are toxic to living organisms.[1] Developing non-toxic, safe-by-design hydrocarbon PEMs is therefore crucial to ensure that renewable technologies that rely on proton exchange membranes remain an environmentally friendly solution. Additional shortcomings of PFSA-based PEMs include their expensive synthetic cost, inherently high hydrogen crossover, and limited operating temperature range due to poor thermo-mechanical properties above 90 °C. Hydrocarbon (HC)-based membranes offer advantages over their perfluorinated counterparts in these specific areas, however, the main drawback of HC-PEMs is that they require a much greater density of sulfonic acid groups to achieve similar proton conductivities as PFSA-based polymers.[2] This leads to greater water uptake and excessive swelling which ultimately leads to reduced mechanical stability of HC membranes.More recently there has been an increasing number of reports exploring the use of block copolymer strategies to limit the water uptake and swelling properties of hydrocarbon PEMs while maintaining good ionic conductivity.[3] As the ion, liquid, and gas transport properties of the membrane are largely attributed to the hydrophilic blocks (i.e., with sulfonic acid groups) and the mechanical, chemical, and thermal stability of the resulting membrane is determined by the hydrophobic blocks (i.e., no sulfonic acid groups), it is postulated that the resulting membrane properties can be tuned by varying the fraction of hydrophilic/hydrophobic blocks.The overall goal of this project is to synthesise hydrocarbon block copolymer PEMs with reduced gas crossover and enhanced the mechanical properties while maintaining sufficiently high ionic conductivity, ultimately leading to higher performance and greater durability inelectrochemical energy conversion and storage systems, e.g., fuel cells and electrolysers. In this project we have compared the ex-situ properties of novel hydrocarbon block copolymers with PFSA-based Nafion membranes, e.g., water uptake and swelling, conductivity measurements, oxidative stability via Fenton's test, etc., as well as in-situ performance tests in single cell fuel cell and electroylzers.[1]Feng, M.; Wang, Z. et al. Sci. Rep. 2015, 5, 9859.[2]Holdcroft, S. Chem. Mater. 2014, 26, 381.[3]Guiver, M. et al. Chem. Rev. 2017, 117, 4759.

Design of novel thermal management system for Li-ion battery module using metal matrix based passive cooling method

Reliable, efficient and safe energy storage is important for electric vehicles and renewable energy storage of power grid. Lithium-ion battery is preferred as energy storage device due to its higher energy density, low self-discharge and longer cycle life. Lithium-ion cells generate heat during high discharge rates and harsh ambient temperature operation, which raises cell temperature and impacts its performance. Therefore, an efficient thermal management system (TMS) is necessary to alleviate thermal issues during charge/discharge process. A combination of phase change material (PCM) with high conductive plate metal matrix is proposed to eliminate the limitation on the heat transfer characteristics of air-cooled systems. To analyze the thermal and electrochemical behavior of a Lithium-ion cell, a detailed CFD simulation with empirical NTGK electro-chemical model is used. The model is first validated with available experimental data and the analysis is then extended to predict thermal response of individual cell of 3s3p module under natural convection boundary conditions. Poor heat transfer capability associated with natural convection at elevated temperature and discharge rate causes the cell maximum temperature (Tmax) and uniformity (ΔT) to be higher than acceptable values of 45 °C and 3 °C respectively. A thermal management system based on passive cooling using PCM is proposed and analyzed using CFD model by first validating the PCM melting behavior under uniform heating. The model is then extended to analyze the impact of PCM on cell temperature rise at different discharge rates of 8 A - 25 A (≈1C - 3.2C) and various operating temperatures of 25°C to 35°C. Low thermal conductivity of PCM limits heat dissipation which leads to higher temperature gradient. A novel TMS based on plate metal matrix structure enclosing PCM is proposed to enhance heat conduction across PCM and increase heat dissipation to maintain battery module under safe operating temperature limits. This approach has brought down the module maximum temperature to 44.1 °C and temperature difference to 1.6 °C during operation at 25 A (3.2C) and 35 °C. Hence, PCM with high latent heat and low thermal conductivity could be used with high conductivity plate metal matrix to improve cell performance by keeping the cell temperature at required range.

Novel Surface Treatment to Mitigate Fouling in Heat Exchangers and Process Equipment

The global impact of climate changes due to greenhouse gas emissions cannot be overemphasized. To combat this, engineers are striving to develop innovative enhancements for heat transfer and fouling reduction in process equipment as a pathway to reduce CO2 emissions. A novel surface application of Minimox® treatment, a water-based suspension of rare-earth oxides, is a promising solution. The self-protective alloy treatment, unlike a traditional continuous coating, has no measurable thickness, does not impose any operating temperature limits, protects from high temperature oxidation, and decreases surface energy and polarity that leads to low fouling and coking rates. Minimox can be applied by dipping or spraying to both external and internal surfaces, including non-conventional tubing shapes. A post-application curing at 400 °C for 1 h is needed to ensure maximum fouling mitigation efficacy. Laboratory tests conducted to simulate operating conditions in a Coker furnace show that the Minimox-treated tubes reduce coke formation by about 80% as compared to untreated tubes. In addition, adhesion of coke to the Minimox treated tubes was significantly lower than for the untreated tubes. Field data collected in refinery applications involving Coker furnace tubes and a vacuum column wash bed are promising, lending support the laboratory results.

A reflection on recent efforts in optimization of cooling capacity of electrocaloric thin films

Despite the advantages of electric field efficiency and miniaturization, the limited operating temperature range and mediocre cooling efficiency of electrocaloric thin films represent the key obstacles to their practical applications in cooling advanced electronics. In this review, we discussed the current efforts and challenges facing the development of high-performance electrocaloric thin films and explored universal approaches along with their physical mechanisms for optimizing the electrocaloric response in thin films. We first emphasize the significance of the indirect method for determining the electrocaloric effect (ECE) in thin films and restate the conditions for the application of Maxwell’s equations. Particularly, we flag a couple of common artifacts of the electrocaloric results induced by the indirect method in recent attempts at the optimization of the ECE. We then cover chemical modification, interface engineering, and strain engineering as effective routes to improve the adiabatic temperature change (ΔT), reduce the driving electric field (E), and widen the operating temperature range (Tspan). At last, we propose that slush relaxors can be exploited as the base system for simultaneously achieving large ΔT, broad Tspan, and low E. Furthermore, we also discuss that the employment of high-entropy oxide perovskites is a feasible approach for greatly raising the dipolar entropy change under low electric fields. At last, we stress the significance and pressing need to measure the EC parameters of thin films with reliable direct methods. We hope that the high-performance electrocaloric thin films and the design rationale discussed in this review could inspire more facile and novel methods to achieve a better electrocaloric response.

Synthesis and NO2 Sensing Properties of In2O3 Micro-Flowers Composed of Nanorods.

Semiconductor oxide gas sensors have important applications in environmental protection, domestic health, and other fields. Research has shown that designing the morphology of sensitive materials can effectively improve the sensing characteristics of sensors. In this paper, by controlling the solvothermal reaction time, a unique hexagonal flower-like structure of In2O3 materials consisting of cuboid nanorods with a side length of 100-300 nm was prepared. The characterization results indicated that with the increase in reaction time, the materials exhibited significant morphological evolution. When the solvent heating time is 5 h, the flower-like structure is basically composed of hexagonal nanosheets with a thickness of several hundred nanometers and a side length of several micrometers. With the increase in reaction time, the apex angles of the nano sheets gradually become obtuse, and, finally, with the Ostwald ripening process, they become cuboid nanorods with side lengths of 100-300 nanometers, forming unique micro-flowers. Among them, the material prepared with a reaction time of 20 h has good sensing performance for NO2, exhibiting low operating temperature and detection limit, good selectivity, repeatability, and long-term stability, thus suggesting a good application prospect.

Thermal management of lithium-ion battery module using the phase change material

One of the significant challenges in the fast adoption of electric vehicles in the market is the thermal management of the battery pack. The current advancement in active and passive cooling techniques is helping resolve this issue in electric vehicles. The present work focuses on the use of passive cooling techniques, such as phase change material (PCM) and the heat sink, to maintain the battery module temperature within the thermal safety limit. The cartridge heaters were used as the mock-up cells. A 3 × 3 array of mock-up cells was formed with a cell-to-cell spacing of 6 mm. OM42 was used as a PCM with a melting point temperature of 44°C and latent heat of fusion, 199 kJ/kg. The experiments were conducted at different power settings of 10–40 W with an interval of 10 W. A heat sink was integrated into the bottom of the battery module. It was observed that increased power input reduces the time required to reach the operating temperature limit of 60°C. After incorporating the PCM, this time was extended by 100.8%, 35.5%, 24.7%, and 21.2% for the power input of 10, 20, 30, and 40 W, respectively. Cell-5 was found to be the most heat-affected cell in the battery module. At higher power inputs of 30 and 40 W, the temperature variation along the height of cell-5 was more than 5°C with and without the PCM. The present findings provide more insights into the heat dissipation at lower and higher power inputs, which may help designers to modify the existing battery thermal management system design efficiently.

Automatized Scaling Monitoring in Pipelines with Resonance Testing

Scaling is a significant cause of efficiency loss, downtime and maintenance costs in almost all industries in which pipelines play an integral role. In this work, a non-invasive, cost-effective and automatized monitoring approach to detect the onset and evolution of scaling growth was developed. The designated field of interest was geothermal plants, which particularly struggle with calcitic scaling in Bavaria. An additional criterion that had to be met was therefore applicability at high temperatures. A resonance testing setup, consisting of automatized excitation using a solenoid-based impactor, piezoelectric acceleration sensors coupled to the pipe, an oscilloscope, a signal conditioner and mounting gear, serves to collect a number of amplitude-time signals. These are Fourier transformed, averaged and evaluated in the frequency domain. By coupling the sensors (standard operating temperature limit ~ 120 °C) to the pipe with a high-temperature couplant and samarium-cobalt magnets, the setup is robust in an environment with elevated temperatures. Such an environment is presented by the injection borehole at a geothermal power plant where in-situ measurements are currently being carried out (60 – 80 °C). It can be observed that the frequency peak positions shift with scaling thickness. In order to analyze this shift in frequency, an experiment was conducted in which a heavily scaled piece of pipeline from the production well of a geothermal power plant in Bavaria was inserted in a specially designed descaling test rig. An acidic solution was pumped through the pipe, gradually etching away the calcitic scaling. By carrying out resonance tests at regular time intervals over the course of the descaling process, a continuous reduction in peak frequencies could be determined with decreasing scaling thickness. With an adequately chosen time interval and appropriate measurement parameters (sampling rate, signal length, gain), the onset- and growth of scaling are measurable in the submillimeter regime.

Сравнительный анализ качества маркировки полимерной и кремнийорганической пленки при обработке волоконным наносекундным лазером

To identify products at all stages of production, a code mark is used by two-dimensional DataMatrix barcoding. Due to the fact that there are different types of surfaces, marking with the help of self-adhesive polymer film materials, where the infor-mation is recorded by a laser using the DPM (Direct Part Marking) method, is becoming increasingly popular. These films, called "laser films", are often used in manufacturing, especially in the automotive industry, as they have a number of ad-vantages compared to other information carriers. However, such films (tesa 6930, 3M 7847) are mostly imported and expen-sive, and also have an operating temperature limit of up to 250 °C, which is sometimes insufficient. The article discusses foreign and domestic films, including polymer NPM012 and organosilicon LP2. LP series are a new group of organosilox-ane–based laser films allowing the use of laser marking for parts operating up to 1000 °C. The article provides a compara-tive analysis of the labeling of polymer films and organosilicon films in accordance with international standards of auto-matic identification and data collection technologies. Laser marking is performed using a nanosecond fiber laser with a power of 30 watts and a wavelength of 1,064 microns. DataMatrix (GS1) is used as a barcode according to the Russian sys-tem of marking and keeping track of goods "Honest Mark". Marking quality assessment is carried out by scanning verifier to check the compliance validation for ISO/IEC standards. The article describes the adjustment of laser barcoding technologi-cal parameters for ensuring high-quality marking.

A High-Sensitivity Cesium Atomic Magnetometer Based on A Cesium Spectral Lamp

Based on a low-noise cesium spectral lamp, a high-sensitivity self-oscillating cesium atomic magnetometer with a wide operating temperature range has been developed, solving problems with existing sensors such as a limited operating temperature range and difficult startup at low temperatures. The temperature feedback mechanism is used to make adjustments to any fluctuations in the cesium lamp’s excitation source in real time, improving the magnetometer’s stability and operating temperature range. Herein, the design and optimization of the cesium atomic magnetometer are presented, and a prototype of the magnetometer is described. The quantum limit sensitivity of the cesium atomic magnetometer is estimated by evaluating the intrinsic relaxation rate in the geomagnetic field. A test demonstrates that the cesium atomic magnetometer’s sensitivity in the geomagnetic background is around 140 fT/Hz at 1 Hz at room temperature, and the operating temperature range is from −50 °C to 70 °C, surpassing most of the commercial products of its kind in terms of sensitivity and operating temperature range.

High-Temperature, Reversible, and Robust Thermochromic Fluorescence Based on Rb2 MnBr4 (H2 O)2 for Anti-Counterfeiting.

Thermochromic fluorescent materials (TFMs) characterized by noticeable emission color variation with temperature have attracted pervasive attention for their frontier application in stimulus-response and optical encryption technologies. However, existing TFMs typically suffer from weak PL reversibility as well as limited mild operating temperature and severe temperature PL quenching. PL switching under extreme conditions such as high temperature will undoubtedly improve encryption security, while it is still challenging for present TFMs. In this work, high-temperature thermochromic fluorescence up to 473 K and robust structural and optical reversibility of 80 cycles are observed in Rb2 MnBr4 (H2 O)2 and related crystals, which is seldom reported for PL changes at such a high temperature. Temperature-driven nonluminous, red and green light emission states can be achieved at specific temperatures and the modulation mechanism is verified by in situ optical and structural measurements and single particle transition. By virtue of this unique feature, a multicolor anti-counterfeiting label based on a broad temperature gradient and multidimensional information encryption applications are demonstrated. This work opens a window for the design of inorganic materials with multi-PL change and the development of advanced encryption strategies with extreme stimuli source.