Exchange Efficiency Research Articles

Influence of castor oil‐derived bio‐resin on mechanical and visco‐elastic properties of dynamic covalent imine bond based epoxy and its composite

AbstractThe widespread use of thermoset composites has raised significant environmental and economic concerns due to their non‐recyclable nature. This study addresses these issues by developing vitrimers and their composites featuring dynamic imine bonds synthesized from vanillin, 3,3′‐dimethyl‐4,4′‐diaminodicyclohexylmethane, and epoxy. To enhance toughness and bio‐content in the vitrimer and its composites, a green reactive monomer, epoxy methyl ricinoleate (EMR), was synthesized via the transesterification of epoxidized castor oil (ECO) and incorporated as the reactive diluent. The effect of EMR on bio‐resin mechanical, thermo‐mechanical, and relaxation times (τ) of the vitrimer was examined. The inclusion of EMR reduced the relaxation time, indicating improved dynamic bond exchange efficiency. EMR incorporation decreased the relaxation time, suggesting enhanced efficiency in the interchange of dynamic bonds. In addition, the incorporation of 20% EMR increased the impact strength of the epoxy vitrimer by 37.8%. The study also details the manufacturing and characterization of greener composites made with these vitrimers and flax fabric, which were evaluated for various mechanical and thermo‐mechanical properties. Morphological analysis using a scanning electron microscope revealed good interfacial adhesion between the fiber and matrix. Furthermore, the flax fiber vitrimer‐based composite demonstrated effective chemical recyclability. The results indicate that these composites possess mechanical and thermal‐mechanical properties well‐suited for lightweight engineering applications.Highlights Recyclable vitrimers were developed from vanillin and epoxy. Toughness and bio‐content were enhanced by adding EMR. Relaxation time was reduced by EMR, improving bond exchange efficiency. Epoxy vitrimer impact strength was increased by 37.8% with 20% EMR. Green composites with vitrimers and flax fabric were manufactured.

Thermal characteristics analysis and cooling model optimization of motorized spindle

Aiming at the influence of poor cooling conditions and traditional cooling control strategy on motorized spindle temperature and machining performance. Firstly, the heat transfer model of the motorized spindle cooling system is studied. Secondly, the influence of coolant inlet flow rate and temperature on the thermal characteristics of the motorized spindle is studied. Then, a thermal network model is established to solve the temperature of each temperature measuring point. Finally, the thermal characteristic experiment of the motorized spindle is carried out, and the cooling fluid flow optimization model is established based on the particle swarm optimization algorithm and simulated annealing algorithm. The results show that the temperature difference of the motorized spindle does not exceed 45 °C, the thermal deformation does not exceed 40.2 μm, and the thermal elongation is inhibited by 36 %. The maximum error of the Thermal Network Method and Finite Element Method（FEM）is 14.24 %. The utilization of the average logarithmic temperature difference for assessing the cooling effectiveness of optimal flow rates revealed that the particle swarm optimization algorithm demonstrates a comparatively lower average logarithmic temperature difference in comparison to the simulated annealing algorithm. The heat exchange efficiency of the motorized spindle is higher under the optimal flow rate obtained by the particle swarm algorithm.

Numerical investigation of the effect of the structure and number of spiral baffles on the vibration and heat transfer coefficient of spiral tubes within spiral tube heat exchangers

In response to the advantages of compactness and high efficiency of spiral elastic tube heat exchanger and its easy-to-vibrate characteristics, this study aims to further improve its heat transfer efficiency by utilizing fluid-induced vibration-enhanced heat transfer technology, so a design scheme of reverse baffle spiral tube heat exchanger (RB-STHE) is proposed to enhance the turbulence characteristics of the shell-side fluid by installing spiral baffles, thus promoting the vibration of the spiral tube. In this study, four new types of the RB-STHE (Model A, B, C, and D) were used as research objects, and the two-way fluid–structure coupling calculation method (using CFX and Transient Structure software) was adopted to systematically investigate the effect of fluid-induced spiral tube vibration on the comprehensive heat transfer coefficient (HTC) of the RB-STHE under different flow velocities and structure schemes, and based on the research data, the objective of no reduction in the comprehensive HTC and savings in the use of materials is taken as the goal, so as to put forward the improved Model C-1. The results show that: although the fluid-induced spiral tube vibration can effectively improve the HTC of the spiral tube, it also increases the pressure drop in the RB-STHE, and the larger the amplitude, the higher the degree of influence; among them, Model C is most affected by the spiral tube vibration, and its HTC and pressure drop are maximally enhanced by 6.33% and 5.85%, respectively. The change in the number of baffles has a significant effect on the comprehensive HTC of the RB-STHE. Compared to the Model D without a spiral baffle, the maximum improvement in the comprehensive HTC of Model C with one spiral baffle installed in the RB-STHE is 14%, while the Model A with four spiral baffles and the Model B with two spiral baffles have a maximum reduction in the comprehensive HTC of 20% and 3%, respectively. In addition, compared to Model C, the structure improved Model C-1 significantly reduces the size of the spiral baffle while effectively maintaining the comprehensive HTC of the RB-STHE, making the structure more reasonable, which provides a reference for heat exchanger design.

Unlocking success: Full year quality and utilization metrics of payer-provider OMH partnership.

41 Background: For more than a decade, CMS and commercial payers have sought to engage provider organizations in value-based cancer care payment models (VBPMs). Success of VBPMs requires payer/provider alignment on quality/utilization measures indicative of high-value care and the efficiency of data exchange between providers and payers. The following describes several key metrics from the first full year 2022 of the Tennessee Oncology (TO) and BlueCross BlueShield of Tennessee (BCBST) Oncology Medical Home (OMH) partnership. Methods: TO and BCBST implemented reporting methodologies for a combination of practice-reported quality and utilization measures and payer claims-based measures: Patient experience, Pathway adherence, Distress screening / interventions, Admissions/1000 patients, ED visits/1000 patients, Imaging utilization, and Observation stays. Bi-weekly meetings between practice and payer were necessary to review quality/utilization measure reporting, coordinate overall program administration, and monitor member attribution for care management and performance-based payments. Results: TO/BCBST co-developed a VBPM that included bi-directional reporting of practice-reported quality and utilization measures and payer claims-based measures. Technical challenges in data sharing and reporting occurred frequently and required regular troubleshooting. Questions regarding trends in observed data arose frequently for both TO and BCBST and required regular discussions between clinical/operational leaders of payer and practice (Table). Conclusions: These data suggest that payers and community oncology practices can co-develop value-based payment models that yield transparency in quality and utilization data reporting, and observed differences in performance and cost-efficiency among different practices in a market. Payers can gain increased transparency in quality and cost-efficiency of cancer care for their members. Practices can leverage care management payments and performance-based payments to support care delivery and quality/utilization data reporting improvements. Provider and payer capabilities to execute transparent QM/UM reporting is a major challenge in implementing OMH programs. 2022 OMH results. Measure % higher or lower than benchmarks Admissions /k -7.0 ED visit /k -8.4 Imaging utilization + 9.4 Observation stays -10.0 Patient experience NA Pathway adherence NA Distress screening / interventions NA Hospice reporting NA NA = not applicable, no benchmark data available/measured; /k = per 1000 patients; negative = lower than benchmarks; positive = higher than benchmarks.

Up-regulation of nitrogen metabolism and chlorophyll biosynthesis by hydrogen sulfide improved photosystem photochemistry and gas exchange in chromium- contaminated bean (Phaseolus vulgaris L.) plants

Hydrogen sulfide (H₂S) is considered as plant growth promoter under heavy metal stress, though its specific effects on photosynthesis are rarely explored. This study investigates the protective effects of exogenous H2S donor sodium hydrosulfide (NaHS) on chlorophyll metabolism and photosystem II (PSII) function in 24-day-old bean plants exposed to 10 μM chromium (Cr) stress. Sodium hydrosulfide (100 μM) reduced Cr accumulation in both roots and leaves, leading to restored plant growth. Concomitantly, H₂S mitigated Cr-induced oxidative damages by decreasing reactive oxygen species levels and further enhancing antioxidant scavenging activities. This resulted in significant reductions in Cr-elevated leaf pheophytin and chlorophyllide levels by 59% and 67%, respectively. Furthermore, NaHS application increased levels of porphyrin and its precursor, 5-aminolevulinic acid (5-ALA), in Cr-stressed bean. The up-regulation in chlorophyll biosynthesis was associated with enhanced activities of glutamine synthetase and glutamate synthase, essential for glutamate (precursor of 5-ALA) production, as well as nitrate and nitrite reductase, leading to increased nitric oxide generation. Under Cr stress, H₂S significantly improved the electron transport rate, effective quantum yield of PSII, and photochemical quenching by 112%, 53%, and 38%, respectively, while reducing non-photochemical quenching by 50%. Furthermore, H₂S promoted net CO₂ assimilation and photosynthesis at saturating light, respectively, while reducing stomatal conductance and transpiration to maintain water balance. Exogenous H₂S restored respiration, as indicated by increased light saturation and compensation points in Cr-treated plants. Overall, these findings indicate that H₂S regulates photosynthesis in Cr-stressed bean by modulating nitrogen and chlorophyll metabolism, thereby optimizing PSII efficiency and gas exchange.

Advancing energy recovery ventilators with phase change materials for cooling load reduction and heat exchange efficiency improvement

Efforts to reduce building energy emissions and achieve net-zero carbon scenarios globally have increasingly focused the building sector on improving energy efficiency. Heating, ventilation, and air conditioning (HVAC) systems play a vital role in providing comfortable indoor environments but significantly contribute to energy consumption and greenhouse gas emissions. Energy recovery ventilators are efficient active systems that prevent unnecessary indoor heat loss and gain, regardless of outdoor climate, making them excellent technologies for achieving zero energy. In a hot and humid summer climate, such as in Korea, it is crucial to enhance the efficiency of energy recovery ventilators and reduce cooling energy consumption. A Green HVAC design aimed at reducing the energy consumption of active systems to near zero was proposed by applying phase change material-based modules with high heat storage performance to energy recovery ventilators. The phase change material module is stabilized with high thermal conductivity aluminum packing and is configured as a mesh-type structure to amplify heat exchange efficiency with air. Compared to the energy recovery ventilator, the application of the module demonstrated a reduction in supply air temperature by an average of 2.6 °C in high-temperature outdoor. During the effective operating period, a continuous indoor intake temperature reduction effect was observed, and the sensible heat exchange efficiency showed a 21.32 % improvement with the module using n-octadecane. Phase change material modules that can enhance ventilation and improve energy efficiency in high-temperature environments can be proposed as a technology to achieve Green HVAC.

Self-assembled nanoflower-mediated interfacial polymerization through tunable intra- and inter-layer channels to boost total heat exchange performance

Total heat exchange membranes (THEMs) are vital for minimizing energy consumption and enhancing indoor air quality in energy recovery ventilation (ERV) systems. Manipulating the surface morphology of polyamide (PA) membranes via nanofiller-mediated interfacial polymerization is key to advancing total heat recovery performance. This study presented the fabrication of PA thin-film nanocomposite (TFN) membranes by integrating self-assembled poly(amic acid-imide) nanoflowers (P(AA-I)-NFs) with intertwined nanosheets into the organic phase. This facile approach effectively eliminated nonselective interphase voids and defects, owing to the superior polymer affinity of the organic nanoflowers. The finely tuned intra- and inter-layer channels within P(AA-I)-NFs significantly impacted monomer mass transfer, facilitated the shuttle effect, expanded the interfacial polymerization zone, and led to the formation of a rougher, thicker PA layer with enhanced surface area. The optimized P(AA-I)-NFs/PA TFN membranes exhibited outstanding performance, including CO₂ permeability of 0.51 GPU, water vapor permeability of 656.59 GPU, and an enthalpy exchange efficiency of 71.47 %, surpassing the trade-off limitations typically observed in commercial and other advanced THEMs. These findings underscored the potential of P(AA-I)-NFs-mediated TFN membranes as highly competitive candidates for next-generation ERV systems.

Parallelization of Curved Inertial Microfluidic Channels to Increase the Throughput of Simultaneous Microparticle Separation and Washing

The rising global need for clean water highlights the importance of efficient sample preparation methods to separate and wash various contaminants such as microparticles. Microfluidic methods for these purposes have emerged but they mostly deliver either separation or washing, with very low throughputs. Here, we investigate parallelization of a curved-channel particle separation and washing device in order to increase its throughput for sample preparation. A curved microchannel applies inertial forces to focus larger 10 µm microparticles at the inner wall of the channel and separate them from smaller 5 µm microparticles at the outer wall. At the same time, Dean flow recirculation is used to exchange the carrier solution of the large microparticles to a clean buffer (washing). We increased the number of curved channels in a stepwise manner from two to four to eight channels in two different arraying designs, i.e., rectangular and polar arrays. We examined efficient separation of target 10 µm particles from 5 µm particles, while transferring the larger microparticles into a clean buffer. Dean flow recirculation studies demonstrated that the rectangular arrayed device performs better, providing solution exchange efficiencies of more than 96% on average as compared to 89% for the polar array device. Our 8-curve rectangular array device provided a particle separation efficiency of 98.93 ± 0.91%, while maintaining a sample purity of 92.83 ± 1.47% at a high working flow rate of 12.8 mL/min. Moreover, the target particles were transferred into a clean buffer with a solution exchange efficiency of 96.81 ± 0.54% in our 8-curve device. Compared to the literature, our in-plane parallelization design of curved microchannels resulted in a 13-fold increase in the working flow rate of the setup while maintaining a very high performance in particle separation and washing. Our microfluidic device offers the potential to enhance the throughput and the separation and washing efficiencies in applications for biological and environmental samples.

Experimental study on the heat storage characteristics of rock bed heat storage system with different packing structure

Establishing energy storage systems can provide an effective solution to the challenges posed by the variability and intermittency of renewable energy sources. Among the available options for energy storage, rock-packed bed thermal energy storage systems are widely favored for their performance, cost-effectiveness, and reliability. The more compact the rock packing, the more adequate the heat exchange of the system; however, poorer permeability increases fluid friction losses and pressure drop, which is detrimental to heat transport within the system. The permeability and heat exchange of the system jointly determines its thermal energy storage performance. This study proposes a composite packing scheme utilizing intact rock slabs and broken rock to enhance the thermal energy storage performance of the packed bed. This approach aims to augment heat exchange efficiency and elevate energy storage density while maintaining the bed's commendable permeability. Heat injection and heat extraction experiments of rock beds were conducted to study the heat storage characteristics of the rock-packed bed thermal storage system under different packing structure. In addition, this study investigates the effect of different injection pressures on the storage and release of heat in the system. The results show that the volume of the pore space of the filled bed, serving as the primary domain for gas flow and gas-rock heat exchange, is a decisive factor affecting the packed bed's permeability and heat exchange performance. When the porosity of the packed bed increased from 5.5 % to 9.9 %, its permeability increased from 1.42 × 10−13 m2 to 3.20 × 10−13 m2, yet the thermal exchange efficiency declined from 67.2 % to 65.3 %. Reasonably arranging intact rock slabs and broken rock fill can alter the path of heat transfer within the packed bed, thereby effectively enhancing its heat storage and release performance. For the same pore volume conditions, the heat exchange efficiency of the packed bed is increased by about 10 % by increasing the number of layers of broken rock fill. Additionally, high gas injection pressures can facilitate heat storage and release processes, but it does not mean that this is more efficient. The research findings can guide the selection of packing and injection schemes in packed bed thermal energy storage systems.

Assessment of Energy Recovery Potential in Urban Underground Utility Tunnels: A Case Study

Underground spaces contain abundant geothermal energy, which can be recovered for building ventilation, reducing energy consumption. However, current research lacks a comprehensive quantitative assessment of its energy recovery. This research evaluates the energy recovery potential of the Xingfu Forest Belt Urban Underground Utility Tunnels. Field experiments revealed a 7 °C temperature difference in winter and a 2.5 °C reduction during the summer-to-autumn transition. A computational fluid dynamics (CFD) model was developed to assess the impact of design and operational factors such as air exchange rates on outlet temperatures and heat exchange efficiency. The results indicate that at an air change rate of 0.5 h−1, the tunnel outlet temperature dropped by 10.5 °C. A 200 m tunnel transferred 8.7 × 1010 J of heat over 30 days, and a 6 m × 6 m cross-sectional area achieved 1.1 × 1011 J of total heat transfer. Increasing the air exchange rate and cross-sectional area reduces the inlet–outlet temperature difference while enhancing heat transfer capacity. However, the optimal buried depth should not exceed 8 m due to cost and safety considerations. This study demonstrates the potential of shallow geothermal energy as an eco-friendly and efficient solution for enhancing building ventilation systems.

Simulation study of heat transfer behaviour of turbulent two-phase flow in a 3D cubic shell and tube heat exchanger using water and different nanofluids

This research utilizes a two-phase flow model to replicate the thermal exchange in a counter flow shell and tube heat exchanger, comparing the efficacy of different nanofluids against pure water. The shell space is represented as a closed cubic area filled with diverse fluids, while the tube functions as the thermal exchange component. It investigates parameters like nanofluid variations, nanoparticle dimensions, and volume ratios to enhance the efficiency of temperature exchange between the shell and tube fluids. The Reynolds-averaged Navier-Stokes (RANS) technique is employed to analyze turbulence within the heat exchanger, utilizing ANSYS@FLUENT (Version 2022 R1) for simulations, which were considered reliable when convergence criteria reached 10−5. The outcomes are assessed based on velocity, thermal conductivity, Nusselt number, temperature dispersion, and turbulent kinetic energy. Notably, the results underscore that integrating nanoparticles into the fluid amplifies its thermal conductivity, with higher concentrations yielding more significant enhancements. Nanofluids, particularly those comprising SiO2-H2O with small nanoparticles and high volume fractions, exhibit notable improvements in heat transfer compared to pure water. TiO2-H2O follows in second place, trailed by CuO-H2O and Al2O3-H2O. The application of the RANS method effectively elucidates turbulence patterns and their impact on heat transfer dynamics between the shell and tube. An increase in Reynolds number has shown an adverse effect on heat transfer. Overall, this study furnishes valuable insights for optimizing heat transfer performance in such systems.

Control of hyperpnoea and pulmonary gas exchange during prolonged exercise: The role of group III/IV muscle afferent feedback.

It remains unclear whether feedback from group III/IV muscle afferents is of continuous significance for regulating the pulmonary response during prolonged (>5min), steady-state exercise. To elucidate the influence of these sensory neurons on hyperpnoea, gas exchange efficiency, arterial oxygenation and acid-base balance during prolonged locomotor exercise, 13healthy participants (4 females; 21 (3) years, : 46 (8) ml/kg/min) performed consecutive constant-load cycling bouts at ∼50% (20min), ∼75% (20min) and ∼100% (5min) of with intact (CTRL) and pharmacologically attenuated (lumbar intrathecal fentanyl; FENT) group III/IV muscle afferent feedback from the legs. Pulmonary responses were continuously recorded and arterial blood (radial catheter) periodically collected throughout the exercise. Pulmonary gas exchange efficiency was evaluated using the alveolar-arterial difference ( ). There were no differences in any of the variables of interest between conditions before the start of the exercise. Pulmonary ventilation was up to 20% lower across all intensities during FENT compared to CTRL exercise (P<0.001) and this hypoventilation was accompanied by an up to 10% lower arterial and a 2-4mmHg higher (both P<0.001). The exercise-induced widening of was up to 25% larger during FENT compared to CTRL (P<0.001). Importantly, the differences developed within the first minute of each stage and persisted, or further increased, throughout the remainder of each bout. These findings reflect a critical and time-independent significance of feedback from group III/IV leg muscle afferents for continuously regulating the ventilatory response, gas exchange efficiency, arterial oxygenation and acid-base balance during human locomotion. KEY POINTS: Feedback from group III/IV leg muscle afferents reflexly contributes to hyperpnoea during short duration (i.e. <5min) locomotor exercise. Whether continuous feedback from these sensory neurons is obligatory to ensure adequate pulmonary responses during steady-state exercise of longer duration remains unknown. Lumbar intrathecal fentanyl was used to attenuate the central projection of group III/IV leg muscle afferents during prolonged locomotor exercise (i.e. 45min) at intensities ranging from 50% to 100% of . Without affecting the metabolic rate, afferent blockade compromised pulmonary ventilation and gas exchange efficiency, consistently impairing arterial oxygenation and facilitating respiratory acidosis throughout exercise. These findings reflect the time-independent significance of feedback from group III/IV muscle afferents for regulating exercise hyperpnoea and gas exchange efficiency, and thus for optimizing arterial oxygenation and acid-base balance, during prolonged human locomotion.

A robust algorithm for authenticated health data access via blockchain and cloud computing.

In modern healthcare, providers increasingly use cloud services to store and share electronic medical records. However, traditional cloud hosting, which depends on intermediaries, poses risks to privacy and security, including inadequate control over access, data auditing, and tracking data origins. Additionally, current schemes face significant limitations such as scalability concerns, high computational overhead, practical implementation challenges, and issues with interoperability and data standardization. Unauthorized data access by cloud providers further exacerbates these concerns. Blockchain technology, known for its secure and decentralized nature, offers a solution by enabling secure data auditing in sharing systems. This research integrates blockchain into healthcare for efficient record management. We proposed a blockchain-based method for secure EHR management and integrated Ciphertext-Policy Attribute-Based Encryption (CP-ABE) for fine-grained access control. The proposed algorithm combines blockchain and smart contracts with a cloud-based healthcare Service Management System (SMS) to ensure secure and accessible EHRs. Smart contracts automate key management, encryption, and decryption processes, enhancing data security and integrity. The blockchain ledger authenticates data transactions, while the cloud provides scalability. The SMS manages access requests, enhancing resource allocation and response times. A dual authentication system confirms patient keys before granting data access, with failed attempts leading to access revocation and incident logging. Our analyses show that this algorithm significantly improves the security and efficiency of health data exchanges. By combining blockchain's decentralized structure with the cloud's scalability, this approach significantly improves EHR security protocols in modern healthcare setting.

ResNet-101 based anomaly detection in additive manufacturing: Thermal modeling for quality control in heat exchanger production

In the production of heat exchangers using additive manufacturing, maintaining consistent quality is a significant challenge due to irregular energy transformations during the manufacturing process. These irregularities can result in faulty products, leading to issues such as reduced efficiency and reliability of the heat exchangers. Traditional quality control methods are often inadequate for real-time detection and correction of such faults. This paper focuses on analyzing the occurrence of faulty products caused by irregular energy transformations in heat exchangers. A deep learning network, specifically ResNet-101, is employed to address this issue. The network is trained with characteristic features of the product and instantaneous variations in the heat exchanger to accurately identify faulty patterns resulting from degradation in the heat exchanger’s performance. By leveraging the deep learning network, which comprehensively understands both the product and heat exchanger features, the system can detect and classify faulty products in real time. This enables immediate corrective actions, such as pushing defective products into a recycling process, thereby maintaining high-quality standards in continuous production.

Thermodynamic Comparative Analysis of Cascade Refrigeration System Pairing R744 with R404A, R448A and R449A with Internal Heat Exchanger: Part 2—Exergy Characteristics

The cascade refrigeration systems (CRS) used in hypermarkets and supermarkets, which are used by many people, have been employing R744 for the low-temperature cycle (LTC) and R404A for the high-temperature cycle (HTC) due to environmental and public safety issues. However, the use of R404A is limited due to its high GWP, and therefore research on alternative refrigerants is necessary. Nevertheless, there is no detailed study in the literature that compares and analyzes the three refrigerants for practical design by applying R744 for LTC and R404A, R448A, and R449A for HTC in CRS. Therefore, this study aims to provide data for the practical detailed design of an alternative system to R744/R404A CRS. Under standard conditions, we analyzed how the exergy destruction rate (EDR) and exergy efficiency (EE) of the system and the EDR of each component change when the important factors affecting CRS (degree of superheating (DSH), degree of subcooling (DSC), and internal heat exchanger (IHX) efficiency of HTC, DSH of LTC, condensation temperature (CT), evaporation temperature (ET), cascade evaporation temperature (CET), and temperature difference of CHX) are varied over a wide range. The main conclusions are as follows. (1) Under the given constant conditions, the smallest change in system EDR based on R448A is DSH of HTC (decreased by 0.07–0.1 kW), followed by IHX of HTC (decreased by 0.12–0.3 kW), DSH of LTC (increased by 0.19–0.25 kW), DSC of HTC (decreased by 0.59–0.69 kW), temperature difference of CHX (increased by 1.57–1.83 kW), CET (decreased and then increased by 0.67–4.43 kW), CT (increased by 1.49–3.9 kW), ET (decreased by 2.39–4.61 kW). (2) The highest change rate of system EE based on R448A is CET (increased and then decreased by 1.38–8.28%), followed by temperature difference of CHX (decreased by 2.96–3.16%), ET (increased and then decreased by 0.63–2.75%), DSC of HTC (increased by 1.26–1.34%), CT (increased and then decreased by 0.24–1.12%), IHX of HTC (increased by 0.11–1.02%), DSH of LTC (decreased by 0.35–0.49%), and DSH of HTC (increased by 0.14–0.19%).

Geologic and thermal conductivity analysis based on geophysical test and combined modeling

Strata thermal conductivity (λe) influences efficiency of medium-depth ground heat exchangers. However, a systematic approach to the acquisition of λe is still lacking. Hence, stratigraphic heat conduction was analyzed using geophysical test in Shenyang, combined with composite modeling. Cenozoic strata (0–730m) exhibited an average λe of 1.32 W·m−1·K−1 due to higher porosity and mud content; Archaean (730–2500m) strata displayed a higher λe of 2.80 W·m−1·K−1, due to dense quartz sandstone with lower porosity and mud content. The CBHE in Shenyang can achieve excellent heat extraction relying on good thermal conduction. Spearman correlation revealed strong negative correlations between λe and acoustic time difference, permeability, and porosity, while positive correlations were observed with depth, resistivity, wave speed, and rock skeleton. Higher rock skeleton thermal conductivity intensified the decrement effect of mud content on λe, while higher mud content diminished the enhancement effect of rock skeleton thermal conductivity. As porosity increased, the decline in λe slowed, particularly pronounced at higher saturation levels. λe exhibited a gradual decrease with temperature, with a more notable change rate observed at lower porosity levels. Principles for enhancing thermal conduction were elucidated through a three-phase analysis. These findings provide foundation for the study and design of medium-depth boreholes.

A detailed analysis of body composition in relation to cardiopulmonary exercise test indices

A cardiopulmonary exercise test (CPET) is a test assessing an individual’s physiological response during exercise. Results may be affected by body composition, which is best evaluated through imaging techniques like magnetic resonance imaging (MRI). The aim of this study was to assess relationships between body composition and indices obtained from CPET. A total of 234 participants (112 female), all aged 50 years, underwent CPETs and whole-body MRI scans (> 1 million voxels). Voxel-wise statistical analysis of tissue volume and fat content was carried out with a method called Imiomics and related to the CPET indices peak oxygen consumption (V̇O2peak), V̇O2peak scaled by body weight (V̇O2kg) and by total lean mass (V̇O2lean), ventilatory efficiency (V̇E/V̇CO2-slope), work efficiency (ΔV̇O2/ΔWR) and peak exercise respiratory exchange ratio (RERpeak). V̇O2peak showed the highest positive correlation with volume of skeletal muscle. V̇O2kg negatively correlated with tissue volume in subcutaneous fat, particularly gluteal fat. RERpeak negatively correlated with tissue volume in skeletal muscle, subcutaneous fat, visceral fat and liver. Some associations differed between sexes: in females ΔV̇O2/ΔWR correlated positively with tissue volume of subcutaneous fat and V̇E/V̇CO2-slope with tissue volume of visceral fat, and, in males, V̇O2peak correlated positively to lung volume. In conclusion, voxel-based Imiomics provided detailed insights into how CPET indices were related to the tissue volume and fat content of different body structures.

A Reduced Resistance, Concentric-Gated Artificial Membrane Lung for Pediatric End-Stage Lung Failure.

The goal of the low-resistance pediatric artificial lung (PAL-LR) is to serve as a pumpless bridge-to-transplant device for children with end-stage lung failure. The PAL-LR doubles the exposed fiber length of the previous PAL design. In vitro and in vivo studies tested hemocompatibility, device flow, gas exchange and pressure drop performance. For in vitro tests, average rated blood flow (outlet SO2 of 95%) was 2.56 ± 0.93 L/min with a pressure drop of 25.88 ± 0.90 mm Hg. At the targeted pediatric flow rate of 1 L/min, the pressure drop was 8.6 mm Hg compared with 25 mm Hg of the PAL. At rated flow, the average O2 and CO2 transfer rates were 101.75 ± 10.81 and 77.93 ± 8.40 mL/min, respectively. The average maximum O2 and CO2 exchange efficiencies were 215.75 ± 22.93 and 176.99 ± 8.40 mL/(min m2), respectively. In vivo tests revealed an average outlet SO2 of 100%, and average pressure drop of 2 ± 0 mm Hg for a blood flow of 1.07 ± 0.02 L/min. Having a lower resistance, the PAL-LR is a promising step closer to a pumpless artificial membrane lung that alleviates right ventricular strain associated with idiopathic pulmonary hypertension.

Systematic Review of IoT-Based Solutions for User Tracking: Towards Smarter Lifestyle, Wellness and Health Management.

The Internet of Things (IoT) base has grown to over 20 billion devices currently operational worldwide. As they greatly extend the applicability and use of biosensors, IoT developments are transformative. Recent studies show that IoT, coupled with advanced communication frameworks, such as machine-to-machine (M2M) interactions, can lead to (1) improved efficiency in data exchange, (2) accurate and timely health monitoring, and (3) enhanced user engagement and compliance through advancements in human-computer interaction. This systematic review of the 19 most relevant studies examines the potential of IoT in health and lifestyle management by conducting detailed analyses and quality assessments of each study. Findings indicate that IoT-based systems effectively monitor various health parameters using biosensors, facilitate real-time feedback, and support personalized health recommendations. Key limitations include small sample sizes, insufficient security measures, practical issues with wearable sensors, and reliance on internet connectivity in areas with poor network infrastructure. The reviewed studies demonstrated innovative applications of IoT, focusing on M2M interactions, edge devices, multimodality health monitoring, intelligent decision-making, and automated health management systems. These insights offer valuable recommendations for optimizing IoT technologies in health and wellness management.

THE DYNAMICAL INVESTIGATION OF HEAT TRANSFER AND TEMPERATURE CHANGES OF THE SHELL AND TUBE HEAT EXCHANGER USING THE LYAPUNOV METHODS

The dynamic of the heat transfer analysis constitutes an important factor that has drawn the attention of many researchers. Heat transfer is evaluated by considering the heat transfer coefficient, the surface area, and the temperature difference between the surface and the surrounding fluid. The computation of the temperature difference across various surface areas shows that increased heat transfer enhances the proportion of the heat conduction rate. In most cases, the system becomes unstable because inappropriate structural elements and outside disturbances, like ambient temperature can readily change the yielding temperature. As a result, the heat exchanger's efficiency needs improvement. A numerical simulation analyzing the performance of a shell and tube heat exchanger indicates that an increase in the surface area leads to a corresponding increase in the heat transfer rate. To optimize system performance, mathematical models were employed for the stability analysis of temperature changes. MATLAB simulations computed temperature differences in quantities of heat and area, thereby obtaining valuable insights for improving heat exchanger design and operation.