Performance Characteristics Research Articles

Biomass and Transparent Supramolecular Elastomers for Green Electronics Enabled by the Controlled Growth and Self-Assembly of Dynamic Polymer Networks.

Determining the optimal method for preparing supramolecular materials remains a profound challenge. This process requires a combination of renewable raw materials to create supramolecular materials with multiple functions and properties, including simple fabrication, sustainability, a dynamic nature, good toughness, and transparency. In this work, a strategy is presented for toughening supramolecular networks based on solid-phase chain extension. This toughening strategy is simple and environmentally friendly. In addition, a series of biobased elastomers are designed and prepared with adjustable performance characteristics. This strategy can significantly improve the transparency, tensile strength, and toughness of the synthesized elastomer. The synthesized biobased elastomers have great ductility, repairability, and recyclability, and they show good adhesion and dielectric properties. A biobased ionic skin is assembled from these biobased elastomers. Assembled ionic skin can sensitively detect external stimuli (such as stretching, bending, compression, or temperature changes) and monitor human movement. The conductive and dielectric layers of the biobased ionic skin are both obtained from renewable raw materials. This research provides novel molecular design approaches and material selection methods for promoting the development of green electronic devices and biobased elastomers.

Biologically inspired piezoresistive MEMS acoustic vector sensor for underwater applications

Underwater acoustics has assumed a pivotal role in the detection, navigation, communication, and target identification of ships and submarines. In recent years, advancements in noise reduction from marine vessels have underscored the significance of underwater acoustic vector sensors. This paper presents a novel approach to the design, fabrication, and characterization of a two-dimensional Micro-Electro Mechanical Systems (MEMS) vector acoustic sensor tailored for underwater environments. Traditional underwater acoustic vector sensors often employ doped polysilicon or silicon/germanium sensing films on rigid silicon substrates. The inflexible nature of silicon substrates necessitates labor-intensive and costly chemical-mechanical polishing processes to achieve submicron thickness, often requiring extended clean-room usage. In contrast, this work proposes a simplified, cost-effective, and scalable alternative. The sensor design utilizes reduced graphene oxide (rGO) as the sensing material and Kapton as the substrate, chosen for their unique properties. rGO exhibits high carrier mobility and low intrinsic noise, ensuring clear signals with minimal external interference, thereby improving measurement accuracy in challenging environments. Kapton provides excellent thermal stability, mechanical strength, and chemical resistance, along with superior insulating properties that reduce electrical noise, enhancing the signal-to-noise ratio. The designed vector sensor leverages the piezoresistive transduction principle, incorporating a thin piezoresistive film of rGO on a flexible Kapton substrate via a straightforward drop-casting method. Inspired by the sensory mechanisms of aquatic life, the two-dimensional vector sensor not only detects pressure associated with acoustic signals but also discerns the direction from which these low and ultralow frequency signals originate. The device's performance characteristics, sensitivity, and directivity are comprehensively evaluated through static, dynamic, and acoustic tests conducted in both air and water mediums. Static tests reveal the piezoresistive behavior of rGO under applied displacement, yielding displacement sensitivities of 0.0279 V/mm and 0.0276 V/mm for axial and radial displacements, respectively. Dynamic and acoustic tests demonstrate the sensor's capability to detect low-frequency signals spanning from 0.25 Hz to 200 Hz, exhibiting a smooth and favorable frequency response. In air, the sensor exhibits receiving sensitivities ranging from −15.18 dB to −19.75 dB (X-channel) and −13.67 dB to −16.67 dB (Y-channel). In the underwater environment, these values range from −134.40 dB to −138.93 dB (X-channel) and −131.83 dB to −136.93 dB (Y-channel). Notably, the variation in receiving sensitivity across channels in both air and water is limited to within 6 dB. Furthermore, the device showcases a symmetrical directivity pattern resembling the shape of an "8," with an approximate sensitivity of −136.66 dB, a significant improvement compared to the −165 dB sensitivity of conventional polysilicon underwater vector sensors. These experimental findings affirm the feasibility of the proposed underwater vector sensor, based on the piezoresistive effect and MEMS technology, highlighting its two-dimensional directivity capabilities.

Effect of dried cauliflower leaf meal (Brassica oleracea var botrytis) dietary supplementation on the growth performance, carcass and meat characteristics of rabbits.

The purpose of this study is to investigate the effect of feeding cauliflower leaf meal (CLM) on growth performance, nutrient utilization, carcass characteristics, histopathology and economics of rabbit production. A total of eighteen 45-day-old Newzeland White rabbits were randomly divided into three groups and fed with control (0%), 20% and 30% CLM in concentrate mixture and feeding trial continued for 3 months. Growth performance was recorded upto the end of the trial. On completion of the growth study, a digestibility trial was conducted to assess the digestibility of nutrients. Afterwards, all the experimental rabbits were slaughtered to evaluate the carcass and meat quality, and to examine histological changes in the viscera. The cost of production was calculated on the basis of partially replacing wheat bran with CLM. Results showed that the body weight gain, feed intake, feed conversion ratio and digestibility of nutrients were similar among the groups of rabbits. Further, dressing percentage, wholesome cut yield, chemical composition of meat, sensory evaluation, water holding capacity and shear force value were also comparable among all groups. However, total phenolic content, vitamin A and E, and polyunsaturated fatty acid were significantly (p < 0.05) higher and 2-Thiobarbituric acid reactive substance was significantly (p < 0.05) lower in 30% CLM-fed group. Histopathological study showed no pathological changes in viscera of rabbits fed with CLM. Moreover, the cost of production was significantly (p < 0.05) lower in 30% CLM-fed group of rabbits. The present work shows that the 30% CLM can be incorporated in concentrate mixture in rabbit diet without affecting growth performance or meat quality and successfully used in rabbit nutrition, which will be cheaper with enhanced keeping quality of meat.

Identification of mycotoxins in yogurt samples using an optimized QuEChERS extraction and UHPLC-MS/MS detection.

Yogurt, a milk-derived product, is susceptible to mycotoxin contamination. While various methods have been developed for the analysis of dairy products, only a few have been specifically validated for yogurt. In addition, these methods are primarily focus on detecting aflatoxins and zearalenone. This study aimed to conduct a preliminary investigation into the presence of regulated, emerging, and modified mycotoxins in natural and oat yogurts available in the Spanish market. For this, a QuEChERS-based extraction method was optimized and then validated to detect and quantify 32 mycotoxins using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The method was in-house validated for the analysis of natural and oat yogurt in terms of linearity, matrix effect, sensitivity, accuracy, and precision. Satisfactory performance characteristics were achieved; for most of the analytes, LOQs were lower than 2ng/g, and recoveries ranged from 60 to 110% with a precision, expressed as the relative standard deviation of the recovery, lower than 15%. Subsequently, the validated method was applied to analyze commercial yogurt samples, revealing a notable incidence of beauvericin and enniatins, with some analogues found in up to 100% of the samples. Alternariol methyl ether was also frequently found, appearing in 50% of the samples. Additionally, the study identified regulated toxins such as fumonisins, ochratoxin A , and HT-2 toxin. These results provide new incidence data in yogurt, raising concerns about potential health risks for consumers.

Spatial Evolution and Driving Factors of Ecological Well-Being Performance in the Yellow River Basin

Ecological well-being performance (EWP) is a key indicator of sustainable development and has garnered significant research attention. This study measures the overall and stage-by-stage efficiency of the urban agglomerations in the Yellow River Basin based on the ends–means framework of steady-state economics. This study then delves into the spatiotemporal transfer characteristics of EWP through Moran’s I, and spatial Markov chains. Additionally, this research investigates the factors influencing EWP using a random forest model. The findings indicate a notable enhancement in EWP in the urban agglomerations in the YRB from 2006 to 2021, showing clear spatial agglomeration patterns. The shift in EWP types displays a “path dependence” effect, with distinct evolutionary paths influenced by spatial lag effects. Ecological input emerges as a key internal driver of EWP, while urbanization and technological advancements are highlighted as significant external factors. Industrial agglomeration and industrial structure also contribute to improving EWP. The findings of this study help to clarify the spatial and temporal characteristics of ecological welfare performance and its driving mechanisms in the urban agglomerations of the Yellow River Basin. This is conducive to the achievement of high-quality urban transformation and regional green development, and it provides a reference for the construction of an ecological civilization.

Optimization and evaluation of modified release solid dosage forms using artificial neural network

This study aims to optimize and evaluate drug release kinetics of Modified-Release (MR) solid dosage form of Quetiapine Fumarate MR tablets by using the Artificial Neural Networks (ANNs). In training the neural network, the drug contents of Quetiapine Fumarate MR tablet such as Sodium Citrate, Eudragit® L100 55, Eudragit® L30 D55, Lactose Monohydrate, Dicalcium Phosphate (DCP), and Glyceryl Behenate were used as variable input data and Drug Substance Quetiapine Fumarate, Triethyl Citrate, and Magnesium Stearate were used as constant input data for the formulation of the tablet. The in-vitro dissolution profiles of Quetiapine Fumarate MR tablets at ten different time points were used as a target data. Several layers together build the neural network by connecting the input data with the output data via weights, these weights show importance of input nodes. The training process optimises the weights of the drug product excipients to achieve the desired drug release through the simulation process in MATLAB software. The percentage drug release of predicted formulation matched with the manufactured formulation using the similarity factor (f2), which evaluates network efficiency. The ANNs have enormous potential for rapidly optimizing pharmaceutical formulations with desirable performance characteristics.

Dietary Crude Protein and Lysine Levels Affect Meat Quality and Myofiber Characteristic of Slow-Growing Chicken

This study aimed to investigate the effects of dietary crude protein (CP) and lysine levels on growth performance, slaughter performance, meat quality, and myofiber characteristics of slow-growing chicken. A 3 × 3 factorial experiment was arranged, and the chickens were fed with 3 levels of dietary CP (16.0%, 17.0%, 18.0%) and 3 levels of dietary lysine (0.69%, 0.84%, 0.99%). A total of 540 8-week-old Beijing-You Chicken (BYC) female growing chickens were randomly allocated to 9 groups, 5 replicates per group, and 12 chickens per replicate. The birds were randomly allocated to one of the 9 experimental diets. Growth performance, slaughter performance, meat quality, and myofiber characteristics were determined at 16 weeks of age. The results showed that dietary CP level and the interaction of dietary CP and lysine levels affected average feed intake (AFI) (p &lt; 0.05). The AFI in the 16.0% CP and 17.0% CP groups was higher than in the 18.0% CP group (p &lt; 0.05). Dietary CP levels significantly affected body weight gain (BWG) (p &lt; 0.05) at 9 to 16 weeks. The 18.0% CP group had the highest BWG (93.99 g). Dietary CP levels affected the percentage of leg muscle yield, and the percentage of leg muscle yield of the 16.0% CP group was significantly lower than that in the other two groups (p &lt; 0.05). Dietary CP and lysine levels alone and their interactions did not affect pH24h, drip loss, and cooking loss of breast muscle (p &gt; 0.05). The shear force of the 18.0% CP group (29.55 N) was higher than that in the other two groups (p &lt; 0.01). Dietary CP level affected myofiber characteristic (p &lt; 0.01), with the lowest myofiber density (846.35 p·mm−2) and the largest myofiber diameter (30.92 μm) at 18.0% CP level. Dietary lysine level affected myofiber diameter, endomysium thickness, perimysium thickness (p &lt; 0.01), with the largest myofiber diameter (29.29 μm) obtained at 0.84% lysine level, the largest endomysium thickness (4.58 μm) at 0.69% lysine level, and the largest perimysium thickness (9.26 μm) at 0.99% lysine level. Myofiber density was negatively correlated with myofiber diameter and endomysium thickness (R = −0.883, R = −0.523, p &lt; 0.01); perimysium thickness had a significant negative correlation with shear force (R = −0.682, p &lt; 0.05). Therefore, reducing dietary CP level and adding appropriate lysine can reduce myofiber diameter and increase perimysium thickness, reducing shear force and improving meat tenderness. A high lysine level (0.99%) in the low-CP (16.0%) diet can improve meat tenderness by regulating the myofiber characteristic without affecting production performance.

Composite Outcome Measures for Psoriatic Arthritis: OMERACT and 3 and 4 Visual Analog Scale Progress in 2023.

The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)-Outcome Measures in Rheumatology (OMERACT) psoriatic arthritis (PsA) working group provided updates at the GRAPPA 2023 annual meeting on its work to evaluate composite outcome measures for PsA. An ongoing systematic literature review is in progress to evaluate psychometric measurement properties using the OMERACT filter 2.2 for a list of candidate composite outcome measures, which include minimal disease activity (MDA), Disease Activity for Psoriatic Arthritis (DAPSA), American College of Rheumatology (ACR) response criteria, Psoriatic Arthritis Disease Activity Score (PASDAS), Composite Psoriatic Disease Activity Index (CPDAI), 3 visual analog scale (3VAS), and 4VAS. The performance of the 3VAS and 4VAS in clinical practice and a synthesis of new data were presented, including estimates for minimal clinically important differences and thresholds of meaning, discrimination and construct validity, and longitudinal construct validity. Numeric rating scale (NRS) versions of the VAS have also been tested. Performance characteristics and psychometric properties are similar to the ASSESS study, a UK multicenter study, indicating that the VAS scales may be feasible tools for routine clinical care with a preference for the 4VAS because of superior face validity and clinical utility.

Performance evaluation of SARS-CoV-2 rapid diagnostic tests in Nigeria: A cross-sectional study.

The COVID-19 pandemic challenged health systems globally. Reverse transcription polymerase chain reaction (RT-PCR) is the gold standard for detecting the presence of SARS-CoV-2 in clinical samples. Rapid diagnostic test (RDT) kits for COVID-19 have been widely used in Nigeria. This has greatly improved test turnover rates and significantly decreased the high technical demands of RT-PCR. However, there is currently no nationally representative evaluation of the performance characteristics and reliability of these kits. This study assessed the sensitivity, specificity, and predictive values of ten RDT kits used for COVID-19 testing in Nigeria. This large multi-centred cross-sectional study was conducted across the 6 geo-political zones of Nigeria over four months. Ten antigen (Ag) and antibody (Ab) RDT kits were evaluated, and the results were compared with RT-PCR. One thousand, three hundred and ten (1,310) consenting adults comprising 767 (58.5%) males and 543 (41.5%) females participated in the study. The highest proportion, 757 (57.7%), were in the 20-39 years' age group. In terms of diagnostic performance, Lumira Dx (61.4, 95% CI: 52.4-69.9) had the highest sensitivity while MP SARS and Panbio (98.5, 95% CI: 96.6-99.5) had the highest specificity. For predictive values, Panbio (90.7, 95% CI: 79.7-96.9) and Lumira Dx (81.2, 95% CI: 75.9-85.7) recorded the highest PPV and NPV respectively. Ag-RDTs had better performance characteristics compared with Ab-RDTs; however, the sensitivities of all RDTs in this study were generally low. The relatively high specificity of Ag-RDTs makes them useful for the diagnosis of infection in COVID-19 suspected cases where positive RDT may not require confirmation by molecular testing. There is therefore the need to develop RDTs in-country that will take into consideration the unique environmental factors, interactions with other infectious agents, and strains of the virus circulating locally. This may enhance the precision of rapid and accurate diagnosis of COVID-19 in Nigeria.

Study on the Road Performance and Compaction Characteristics of Fiber-Reinforced High-RAP Plant-Mixed Hot Recycled Asphalt Mixtures

Recycled asphalt pavement (RAP) mixtures are widely adopted due to their significant economic and social benefits from utilizing pavement recycling materials. This study incorporates basalt fibers (BF) and polyester fibers (PF) into plant-mixed hot recycled asphalt mixtures to analyze their enhancement effects on the high-temperature, low-temperature, and fatigue performance at different RAP content levels. Additionally, the study investigates the impact of fiber and RAP additions on the compaction characteristics of the mixtures using gyratory compaction tests, aiming to increase the RAP content of plant-mixed hot recycled asphalt mixtures. Experimental results demonstrate that at 30% and 50% RAP content levels, basalt fibers exhibit more pronounced enhancement effects on the performance of recycled asphalt mixtures compared to polyester fibers. Incorporating basalt fibers increases the fracture energy of recycled asphalt mixtures by 8.63% and 13.9%, and improves fatigue life by 154% and 135%, respectively. Moreover, the addition of both types of fibers increases compaction difficulty, with polyester fibers showing a more significant influence on the compaction energy index (CEI).

Grating Structures for Silver-Based Surface Plasmon Resonance Sensors with Adjustable Excitation Angle

Silver-based grating structures offer means for implementing low-cost, efficient grating couplers for use in surface plasmon resonance (SPR) sensors. One-dimensional grating structures with a fixed periodicity are confined to operate effectively within a single planar orientation. However, two-dimensional grating structures as well as grating structures with variable periodicity allow for the plasmon excitation angle to be seamlessly adjusted. This study demonstrates silver-based grating designs that allow for the plasmon excitation angle to be adjusted via rotation or beam position. The flexible angle adjustment opens up the possibility of developing SPR sensor designs with an expanded dynamic range and increased flexibility in sensing applications. The results demonstrate that efficient coupling into two diffraction orders is possible, which ultimately leads to an excitation angle range from 16° to 40° by rotating a single structure. The findings suggest a promising direction for the development of versatile and adaptable SPR sensing platforms with enhanced performance characteristics.

Compact Modified Elliptical-Shaped Ultra-wideband Filtering Antenna with Improved Band-Edge Selectivity

A compact filtering antenna with higher selectivity near band-edge frequencies for ultra-wideband (UWB) applications is presented and developed in this article. The antenna with filtering characteristics is formulated by integrating a rectangular-impedance resonator-based bandpass filter into the feedline of a modified elliptical-shaped monopole radiator. Initially, a modified elliptical-shaped monopole radiator is designed and numerically simulated to ensure the overall performance over the UWB band. The modified elliptical shape is used as a radiator to increase the electrical length while maintaining minimum physical size. The size of the UWB antenna is merely 0.518λ AL × 0.272 λ AL (where λAL is the guided wavelength at 2.62 GHz). Furthermore, to enhance the performance characteristics of the filtering antenna along with band-edge selectivity, geometrical parameters are optimized using a numerical simulation tool. It exhibits a simulated impedance bandwidth of 112% (3.05–10.81 GHz) with an electrical size of 0.676λ FL × 0.316λ FL (where λFL is the guided wavelength at 3.05 GHz). The experimental results of the fabricated UWB antenna and filtering antenna prototypes agree well with their simulated results.

Overview of Patents on Diamond Polishing Apparatus

Diamond, with its unparalleled combination of physical and chemical attributes, occupies a critical role in future technological domains; yet, the caliber of its surface quality is decisively linked to its performance within advanced applications. Thus, engaging in super-precision processing to elevate the surface integrity of diamond constitutes a central tenet for broadening its application potential. This paper systematically dissects patents pertaining to diamond polishing apparatus, not only revealing the distinctive strengths and pragmatic features inherent in contemporary diamond polishing technology but also identifying limitations and avenues for refinement within current polishing methodologies. With the continuous expansion and deepening of modern industrial sectors, there is a growing demand for diversified and specialized material performance. Diamond, as a pivotal raw material, exhibits immense potential in its composite applications with a variety of other materials, forming an entire industrial chain that has permeated numerous industries. Throughout the comprehensive preparation process of diamond, from rough stone to finished product, polishing techniques play a critical role, representing an indispensable step in enhancing the surface quality and functional attributes of diamond products. This study provides a comprehensive review of representative patents in the field of diamond polishing apparatus, analyzing the distinctive functional attributes and performance characteristics of various diamond polishing devices. The study classifies polishing devices according to their design characteristics and application domains into five distinct categories: polishing apparatuses specifically designed for single-crystal diamonds, systems tailored for the polishing of complex curved surface diamonds, laser-assisted diamond polishing setups, structurally-enhanced diamond polishing equipment, and functionally-specialized diamond polishing tools. The analysis underscores the unique innovative aspects and advantages demonstrated by each patent in addressing the inherent limitations of traditional polishing devices. Moreover, it elucidates the technological constraints and developmental gaps that exist within each respective area. Presently, the essence of polishing technology research revolves around the precision and efficacy in polishing single-crystal diamonds and intricate curved diamond surfaces, alongside the structural innovation and functional refinement of polishing apparatuses. Predominant among these devices are those that largely depend on mechanical polishing methods integrated with laser-assisted and chemical mechanical polishing methodologies, where patent advancements are mainly geared towards boosting efficiency, guaranteeing surface integrity, fortifying adaptability across different operating scenarios, and incorporating multiple functionalities. Concurrently, considerable attention is given to enhancing the ecological performance of these systems. There remains a significant underdevelopment and limited widespread application of diamond polishing apparatus in advanced technologies such as thermal chemical polishing and ion beam polishing. This gap presents an enormous potential for innovation breakthroughs and diversified advancements in polishing techniques. There is an urgent need for increased investment to propel the development and integration of automated control systems, intelligent monitoring, and deeper exploration of new materials within polishing technology. The aim is to realize higher-level automated and intelligent diamond polishing solutions that can achieve more efficient, precise, and environmentally friendly polishing objectives.

STOP-Bang questionnaire in patients hospitalized with acute symptomatic pulmonary embolism.

The STOP-Bang questionnaire is a validated screening tool for obstructive sleep apnea (OSA). We conducted this study to validate it among patients hospitalized with acute symptomatic pulmonary embolism (PE). This prospective cohort study enrolled consecutive stable patients with acute PE who underwent an overnight sleep study within 7 days after diagnosis. Our outcomes were: i) the STOP-Bang questionnaire's utility for risk stratification, ii) the discrimination of the STOP-Bang questionnaire categories, iii) the false negative rate of STOP-Bang questionnaire prediction, and iv) the clinical utility of the STOP-Bang questionnaire to exclude OSA. We also calculated the test performance characteristics to predict OSA. During the study period, 268 patients completed a sleep study. OSA was found in 47% of patients. OSA incidence in low-, moderate-, and high-risk STOP-Bang groups was 22.4%, 48.2%, and 61.5%, respectively (P <0.001). The area under the receiver operating characteristics curve of the STOP-Bang questionnaire for risk of OSA was 0.65. The false negative rate of a low-risk STOP-Bang questionnaire result to rule out OSA was 22.4% and the clinical utility was 21.6%. The sensitivity was 89.8% (97.2% for men and 80.4% for women). The STOP-Bang questionnaire showed poor discrimination for the risk of OSA in hospitalized patients with acute symptomatic PE. It had a high false negative rate and a low clinical utility. The STOP-Bang questionnaire had a good sensitivity in men, and might be used to rule out OSA in this population.

The Physiological and Performance Development of Two Multiple Olympic Champion Rowers: A 20-Year Follow-Up Study.

This study reports the results of a 20-year (2005-2024) follow-up study of two 2-time Olympic and 6-time world champion rowing athletes. To provide a comprehensive picture of adaptations in physiological and performance characteristics to long-term training, we monitored the athletes' physiological and performance data annually through five 4-year developmental phases. Maximal oxygen uptake (V̇O2max), maximal minute power (MMP), and power output corresponding to anaerobic threshold (PAT) were derived from a ramp-wise exercise test on a rowing ergometer. Additionally, average power output sustained during all-out tests over 2000-m and 6000-m on a rowing ergometer was also obtained. V̇O2max peaked at age 22 for Athlete A and at age 25 for Athlete B (at ~7 L·min-1), before stabilizing and then gradually declining to a range of 6.2-6.5 L·min-1 for both athletes. MMP stabilized in both rowers at values between 550 and 575 W and displayed minimal fluctuations over the final two phases of the study. Additionally, MMP closely resembled the corresponding average power output sustained during the 2000-m all-out tests on a rowing ergometer. Average power output during 2000-m and 6000-m all-out tests showed steady improvements over the monitored phases of the study, with highest power output crew averages for both 2000-m (532 W; 5 min 48 s) and 6000-m (463 W; 18 min 4 s) tests recorded during the last 4-year phase of the assessment. Improvements in rowing ergometer performance over 2000-m and 6000-m appear to be largely independent of the multi-year changes in V̇O2max. Long-term rowing training resulted in continuous improvements in MMP and PAT throughout the monitored phases, which more closely mimicked improvements in rowing ergometer performance.

Experimental investigation of a transcritical CO2 refrigeration system incorporating rotary gas pressure exchanger and low lift ejectors

Natural refrigerants like CO2 are playing a significant role in making refrigeration and heat pump systems climate-friendly by slowly phasing out the high global warming refrigerants like hydrofluorocarbons (HFCs). However, the efficiency of a transcritical CO2 refrigeration system declines significantly when the ambient temperature increases, primarily attributed to the high-pressure lift and the losses incurred during expansion. To remedy this issue, this paper presents a novel rotary gas pressure exchanger (PXG) device, which simultaneously achieves high differential pressure expansion work recovery and the “free compression” of the portion of the flash gas in a compact, rotary machine. For this, a PXG device is designed, fabricated, and tested to achieve free compression of CO2 over the entire differential pressure of approximately 70 bar between a receiver and a gas cooler. This is one of the highest free-pressure lift provided by any device to date in CO2 refrigeration. However, there is a small pressure loss of approximately 1–2 bar in the system due to viscous and inertia losses in the piping and in the PXG itself, which needs to be overcome by an external booster device. Results on a baseline PXG integrated system with two low lift booster compressors are presented, which show up to 60 bar free pressure lift and up to 18.2 % COP improvement provided by PXG. Additionally, key performance characteristics of the PXG, like the expansion work recovery, the mass boost ratio, direct fluid-to-fluid contact, and no pass-through operation are experimentally quantified. This work also presents a novel method to integrate two low lift ejectors with PXG to eliminate the need for separate low lift compressors. The low lift ejectors are designed, fabricated, and tested in-house, followed by their integration with the PXG device. A new type of transcritical CO2 refrigeration system is designed to integrate these low lift ejectors with PXG, and experiments are conducted at various evaporator thermal duties and gas cooler exit temperatures, simulating varying ambient temperature conditions. A novel control system to control the gas cooler pressure to optimal thermodynamic levels using PXG rotational speed is demonstrated experimentally. Further, automated control of high-pressure low lift ejector mass flow using an in-built needle design has been successfully demonstrated to optimise PXG mass boost performance. The LP low lift ejector achieved a successful pressure lift of 3.8 bar, and the HP low lift ejector showed a lift of 5.7 bar on the top of 42 bar free pressure lift provided by PXG for up to 5.8 kg/min mass flow delivered by free PXG compression. The results from this study demonstrate that the PXG device provides a significant energy efficiency improvement to the transcritical CO2 refrigeration system, and the novel low lift ejectors, when integrated with PXG, provide a successful method to maximise PXG’s thermodynamic potential.

Experimental investigation on cooling performance and heat transfer characteristics of the ribbed endwall with upstream leakage

In this paper, the merits and demerits of endwall modification by designing micro-scale ribs onto the turbine endwall surface was examined experimentally for two aspects: cooling performance and heat transfer characteristics. The experiment was conducted on ribbed endwall with three rib directions (horizontal, vertical and tiled rib) and two rib spacings (8 mm and 10 mm) and compared with the flat endwall. The measurement of heat transfer was conducted with a high-resolution infrared thermal camera and that of cooling effectiveness (η) was conducted with pressure-sensitive paint technique. Results showed that the direction of rib and rib-induced vortex greatly affects the coverage of coolant, which the tilted and vertical ribbed endwall demonstrated positive effects on film cooling. Additionally, the heat transfer of the ribbed endwall is also connected with the layout of the rib and mainly depends on the joint influence of the rib-induced vortex and passage vortex. The Nusselt number (Nu) of the vertical rib was the smallest. In general, vertical rib with larger rib spacing shows the comprehensive performance, that an increase of 9.5% for area-averaged η than original endwall with mass flow rate of 1.0% and the least increase of Nu, which can provide guidelines for future cooling design.

Performance Evaluation of Fractional Proportional–Integral–Derivative Controllers Tuned by Heuristic Algorithms for Nonlinear Interconnected Tanks

This article presents an in-depth analysis of three advanced strategies to tune fractional PID (FOPID) controllers for a nonlinear system of interconnected tanks, simulated using MATLAB. The study focuses on evaluating the performance characteristics of system responses controlled by FOPID controllers tuned through three heuristic algorithms: Ant Colony Optimization (ACO), Grey Wolf Optimizer (GWO), and Flower Pollination Algorithm (FPA). Each algorithm aims to minimize its respective cost function using various performance metrics. The nonlinear model was linearized around an equilibrium point using Taylor Series expansion and Laplace transforms to facilitate control. The FPA algorithm performed better with the lowest Integral Square Error (ISE) criterion value (297.83) and faster convergence in constant values and fractional orders. This comprehensive evaluation underscores the importance of selecting the appropriate tuning strategy and performance index, demonstrating that the FPA provides the most efficient and robust tuning for FOPID controllers in nonlinear systems. The results highlight the efficacy of meta-heuristic algorithms in optimizing complex control systems, providing valuable insights for future research and practical applications, thereby contributing to the advancement of control systems engineering.

Performance characteristics of ultra-thin flat plate oscillating heat pipes with alternate channels and auxiliary micro-grooved structures

Two flat plate oscillating heat pipes (FPOHPs) characterized by the same thickness of 1 mm and alternating channel widths were fabricated using the wet etching technique. HFE-7100 was used as a working fluid at volumetric filling ratios ranging from 30%–60%. The startup and heat transfer characteristics of FPOHPs with and without embedded parallel microgrooves on the bottom wall of wider channels were experimentally compared and evaluated. The dual-diameter FPOHPs could operate at both horizontal and vertical orientations. The introduction of microgrooves reduced the duration of the startup time, lowered the startup temperature, and avoided the temperature overshoot. Furthermore, the microgrooves significantly reduced the temperature of the evaporator. At the combined condition of 30% filling ratio and 24 W power input, the effective thermal conductivities (ETCs) of the FPOHP with microgrooves were 1241 and 1226 W/(m·°C), respectively, at horizontal and vertical orientations, approximately 25.6% and 18.8% higher than those without microgrooves, or approximately 3.1 times higher than pure copper. At the horizontal orientation, the heat transfer enhancement was more pronounced for the micro-grooved FPOHP compared to that without micro-grooves. The micro-grooved structures facilitated the unidirectional fluid circulation and reduced the gravity dependence, showing the application prospects at both terrestrial and microgravity conditions.

Artificial Perovskite Multiple Quantum Well Optoelectronics

Metal halide perovskite-based photovoltaics and light-emitting diodes (LEDs) have exhibited a promising trajectory toward commercial viability, nearing the performance levels of them to the commercially established materials. A particularly encouraging avenue involves tailoring the various dimensions of perovskite materials, notably through the implementation of perovskite multiple quantum wells (MQWs), to amplify their potential in optoelectronic applications. This comprehensive review delves into recent breakthroughs in both self-assembled perovskite MQWs and artificially fabricated counterparts, elucidating their mechanisms and performance characteristics. By gathering and evaluating the very original and the latest research findings, this review aims to provide valuable insights into the underlying principles governing optical behaviors of perovskite MQWs as well as optoelectronic and photonic applications. Furthermore, it outlines prospective research pathways, delineating potential pathways for further exploration and optimization of perovskite MQW-based devices. Through this general evaluation on the recent advancements and prospects, this review contributes to advancing the understanding and application of perovskite materials in next-generation optoelectronic and photonic technologies.