Cycle Temperature Research Articles

Alginate-based functionalized, remote, light-responsive hydrogel transducer for synergistic mild photo thermoelectric stimulation for tumor therapy

Photothermal therapy (PTT) is an effective cancer treatment that circumvents the resistance caused by chemotherapy drugs. Conventional PTT has a relatively high temperature, which is better able to kill tumor tissues, but it is also more damaging to normal tissues. Mild PTT avoids these high temperatures, but its corresponding killing ability becomes lower and enhances the heat resistance of cancer cells, causing tumor self-protection and reducing the therapeutic effect of PTT. Here, we reported a new, remotely stimulable, mild-temperature PTT combined with electrical stimulation-induced ionic interference therapy. We introduced MXenes into alginate based thermoresponsive PVA/P(NIPAm-co-SA) hydrogel (PPS) to formulate mechanically reliable hydrogel electrolyte-based supercapacitors as an ion homeostasis perturbator. The artificially controlled duration of near-infrared radiation modulates the PTT cycle temperature, which is controllably maintained at a little under 45 °C to reduce Hsp90 overexpression. Light-induced phase transitions in the hydrogel produce voltages that resemble low-intensity, alternating electric fields. Moreover, chronic piezoelectric stimulation can inhibit cancer cell proliferation by upregulating the expression of genes encoding Kir3.2 inwardly rectifying potassium channels, by interfering with Ca2+ homeostasis, and by affecting mitotic spindle organization during mitosis. In vivo and in vitro antitumor studies on the 4T1 model suggest that this functionalized, remote, light-responsive transducer is an effective and promising tool for the treatment of tumors.

An in vitro study of irrigation rate, operator duty cycle and intrarenal temperature in superpulse fiber thulium laser lithotripsy

ObjectiveThe present study aimed to examine the relationship between irrigation velocity, operator duty cycle (ODC), and intrarenal temperature during retrograde intrarenal surgery with a superpulse fiber thulium laser.MethodsPlace the stones into the fresh isolated porcine kidneys, use puncture needle to place the temperature probe 2 mm around the stones, and place the pressure probes in the upper calyx, lower calyx, and renal pelvis. Place the entire setup in a 37 °C constant temperature water bath to simulate the human body environment. The laser power varies between 10 and 30 W, and the irrigation speed is 10-30 ml/min. Additionally, at a laser power of 20 W and an irrigation speed of 10 ml/min, different On-Duty Cycles (ODC) are set. Monitor the changes in temperature and pressure.ResultsA direct proportionality of temperature in the kidney to the rate of irrigation has been reported between 10 W and 30 W laser powers. The percentage ratio of the rate of irrigation and power in the laser is 1:1, which can keep the temperature in the kidney at a safe level. At a laser power of 20 W and irrigation of 10 ml/min, the temperature inside the kidney increases sharply with the increase in ODC. By decreasing the ratio of ODC, the increase of temperature inside the kidney can be brought to a great reduction.ConclusionMaintaining a 1:1 ratio between laser power and irrigation speed can effectively prevent thermal damage or injury to kidney tissue.Additionally, by adjusting the On-Duty Cycle (ODC) ratio, the intrarenal temperature can also be reduced.

Importance of Clay Swelling on the Efficacy of Cyclic Steam Stimulation in the East Moldabek Formation in Kazakhstan

Both steam and hot water flooding of high-viscosity oils in the presence of swelling clays are difficult methods for producing oil efficiently because of potential formation permeability reduction. This paper pertains to heavy oil recovery from the East Moldabek formation where the oil API gravity is about 22 and is inundated with swelling clays. To achieve this, we used the IntersectTM reservoir simulator to compare oil recovery economics using both hot water and steam injection as a function of steam cycle duration, temperature, and steam dryness. We also studied clay swelling in the East Moldabek formation where clay poses a significant challenge due to its impact on permeability reduction. In this research, we developed an equation based on experimental data to establish a relationship between water mineralization and permeability in the East Moldabek formation. The equation provides valuable insight on how to mitigate clay swelling which is crucial for enhancing oil recovery efficiency—especially in sandstone reservoirs. Our modeling studies provide the recovery efficiencies for salinities of the hot water EOR versus cyclic steam EOR methods in a formation containing swelling clays. Specifically, the reduction in formation permeability as a function of the distilled water fraction is the controlling parameter in hot water or steam flooding—when the formation water mixture becomes less saline, oil recovery decreases. Our research shows that clay swelling can significantly impact cyclic steam stimulation outcomes, potentially reducing its effectiveness, while hot water flooding may offer a more cost-effective and operationally feasible solution in formations where clay swelling is a concern. Economic analysis reveals the potential for achieving an optimal favorable condition for hot water injection. Therefore, this paper provides a guideline on how to conduct thermal oil recovery for heavy oils in fields with high clay content such as the East Moldabek deposit.

A durable cobalt catalyst supported on Ni foam coated with Al2O3 for hydrogen generation from NaBH4 hydrolysis

A durable cobalt catalyst supported on Ni foam coated with Al2O3 (Co/Al2O3–Ni foam) is developed and analyzed using various analytical methods. In addition, the catalyst is tested to investigate the effects of the Al2O3 coating cycle, Co reduction cycle, and reaction temperature on hydrogen generation from NaBH4 hydrolysis. The Al2O3 coating cycle considerably affects hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. However, the Co reduction cycle and reaction temperature slightly affect hydrogen generation and the catalyst area required for a hydrogen generation rate of 1 L/min. The catalyst exhibits an apparent activation energy of 64.3 kJ/mol, which is relatively higher than those of the other catalysts. Furthermore, the catalyst exhibits durability comparable to that of other catalysts. Thus, the Co/Al2O3–Ni foam catalyst with high apparent activation energy and comparable catalytic durability is suitable for the NaBH4 hydrogen generation system.

Deepening the Decade: Collaborative Action for Advancing Deep‐Ocean Science and Policy in the United Nations Decade of Ocean Science for Sustainable Development

AbstractThe current United Nations Decade of Ocean Science for Sustainable Development (2021–2030; hereafter, the Decade) offers a unique opportunity and framework to globally advance ocean science and policy. Achieving meaningful progress within the Decade requires collaboration and coordination across Decade Actions (Programs, Projects, and Centres). This coordination is particularly important for the deep ocean, which remains critically under‐sampled compared to other ecosystems. Despite the limited sampling, the deep ocean accounts for over 95% of Earth's habitable space, plays a crucial role in regulating the carbon cycle and global temperatures, and supports diverse ecosystems. To collectively advance deep‐ocean science, we gathered representatives from 20 Decade Actions that focus at least partially on the deep ocean. We identified five broad themes that aim to advance deep‐ocean science in alignment with the Decade's overarching 10 Challenges: natural capital and the blue economy, biodiversity, deep‐ocean observing, best practices in data sharing, and capacity building. Within each theme, we propose concrete objectives (termed Cohesive Asks) and milestones (Targets) for the deep‐ocean community. Developing these Cohesive Asks and Targets reflects a commitment to better coordination across deep‐ocean Decade Actions. We aim to build bridges across deep‐ocean disciplines, which encompass natural science, ocean observing, policy, and capacity development.

Performance Evaluation of CO2 + SiCl4 Binary Mixture in Recompression Brayton Cycle for Warm Climates

This work demonstrates the potential of CO2 + SiCl4 binary mixture as a working fluid for power generation cycle. Recompression Brayton cycle configuration is considered due to its proven record of high performance for medium- to high-temperature sources. The objective of this study is to assess the thermodynamic performance of a recompression Brayton cycle using a CO2 + SiCl4 binary mixture as a working fluid, particularly under warm climate conditions. The cycle is simulated using the Peng–Robinson equation of state in Aspen Hysys (v11) software, and the model is validated by comparing VLE data against experimental data from the literature. The analysis involves the assessment of cycle’s thermal efficiency and exergy efficiency under warm climatic conditions, with a minimum cycle temperature of 40 °C. The results demonstrate a notable improvement in the cycle’s thermodynamic performance with CO2 + SiCl4 binary mixture compared to pure CO2. A small concentration (5%) of SiCl4 in CO2 increases the thermal efficiency of the cycle from 41.7% to 43.4%. Moreover, irreversibility losses in the cooler and the heat recovery unit are significantly lower with the CO2 + SiCl4 binary mixture than with pure CO2. This improvement enhances the overall exergy efficiency of the cycle, increasing it from 62.1% to 70.2%. The primary reason for this enhancement is the substantial reduction in irreversibility losses in both the cooler and the HTR. This study reveals that when using a CO2 + SiCl4 mixture, the concentration must be optimized to avoid condensation in the compressor, which can cause physical damage to the compressor blades and other components, as well as increase power input. This issue arises from the higher glide temperature of the mixture at increased SiCl4 concentrations and the limited heat recovery from the cycle.

High-temperature fretting wear behavior and microstructure stability of a laser-cladding Ti-Al-C-N composite coating meditated by variable cycle conditions

Ti-6Al-4 V titanium alloy is used for low-pressure compressor blades of aero-engine due to its high specific strength, excellent corrosion resistance and high-temperature stability. Low-pressure compressor blades are subject to fretting wear in service, which may lead to fracture failure of the blades. The preparation of wear-resistant coatings is currently an effective solution in solving the problem of fretting wear on Ti-6Al-4 V titanium alloy. However, the fretting wear resistance and microstructure stability of the coating under variable cycle fretting conditions require more attention. In this work, the fretting wear performance and microstructure stability of the Ti-Al-C-N composite coating under variable cycle fretting conditions are investigated. The results show that the parameters of variable cycle operating conditions have a notable effect on the coefficient of friction (COF). The variable frequency and variable temperature working conditions result in the alteration of the fretting operation mechanism. Whereas the variable stroke amplitude and the variable load conditions do not cause changes in the fretting operation mechanism, and both are in the gross slip region (GSR). The lowest wear rate occurs under variable stroke amplitude conditions. The wear rate is the maximum under the variable cycle temperature condition. According to the dissipated energy calculation, the difference between the two different stroke amplitudes is the biggest among all the conditions. EBSD and TEM analyses show that the subsurface of variable stroke amplitude worn scar has a more uniform strain distribution, and reveals a unique subsurface structure with a transformation from crystalline to amorphous, which contributes to improving the wear resistance. This work provides insights into coating microstructure stability and wear mechanisms under variable cycle conditions.

Mechanism of interfacial thermal resistance variation in diamond/Cu/CNT tri-layer during thermal cycles

The multilayer materials in aerospace applications generally subject to thermal shock, which may significantly affect the interfacial thermal resistance (ITR) and cause serious overheating issues. Therefore, understanding the interfacial thermal transport under temperature shock is essential for effective thermal management in aerospace devices. In the present study, the variation in ITR within the diamond/Cu/carbon nanotube tri-layer after thermal cycles was investigated through non-equilibrium molecular dynamics (NEMD) simulations. We conducted four groups of investigations, exploring the impact of maximum cycle temperature, heating/cooling rates, number of cycles, and interfacial structure on ITR. The results demonstrate that while the matching degree of phonon density of states remains almost constant, the ITR varies significantly among all groups. The structural deformations and changes in lattice type can be observed in the Cu layer. Based on these findings, we proposed an “atomic distribution method” to elucidate the mechanism behind ITR variation, which was verified as applicable and precise. Additionally, the thermal rectification results demonstrate the significant effect of interfacial structure on the rectification coefficient, indicating that interfacial transport and lattice thermal conduction deserve more in-depth study in the future. This work provides a novel perspective on understanding thermal transport across the irregular and complex interfaces, which is significant for the thermal management in aerospace field.

Implementation of Rapid Nucleic Acid Amplification Based on the Super Large Thermoelectric Cooler Rapid Temperature Rise and Fall Heating Module.

In the rapid development of molecular biology, nucleic acid amplification detection technology has received more and more attention. The traditional polymerase chain reaction (PCR) instrument has poor refrigeration performance during its transition from a high temperature to a low temperature in the temperature cycle, resulting in a longer PCR amplification cycle. Peltier element equipped with both heating and cooling functions was used, while the robust adaptive fuzzy proportional integral derivative (PID) algorithm was also utilized as the fundamental temperature control mechanism. The heating and cooling functions were switched through the state machine mode, and the PCR temperature control module was designed to achieve rapid temperature change. Cycle temperature test results showed that the fuzzy PID control algorithm was used to accurately control the temperature and achieve rapid temperature rise and fall (average rising speed = 11 °C/s, average falling speed = 8 °C/s) while preventing temperature overcharging, maintaining temperature stability, and achieving ultra-fast PCR amplification processes (45 temperature cycle time < 19 min). The quantitative results show that different amounts of fluorescence signals can be observed according to the different concentrations of added viral particles, and an analytical detection limit (LoD) as low as 10 copies per μL can be achieved with no false positive in the negative control. The results show that the TEC amplification of nucleic acid has a high detection rate, sensitivity, and stability. This study intended to solve the problem where the existing thermal cycle temperature control technology finds it difficult to meet various new development requirements, such as the rapid, efficient, and miniaturization of PCR.

Coupling study of onboard power generation system of Magnetohydrodynamics enhanced Brayton Cycle

Closed cycle power generation systems offer a possible solution to meet the high electricity needs of hypersonic vehicles, but the power generation is limited by the finite cold source and cycle temperature. Introducing two-phase flow liquid metal (LM) MHD power generation based on Closed-Brayton-Cycle (CBC) is a potential solution that can enhance the thermal-electricity conversion process at the system level. However, it is difficult to reflect the complex coupling relationship between the power generation system and the vehicles propulsion system and the limitations of finite cold sources by relying only on ideal system analysis, especially the contradiction between the void fraction and the mass flow of working fluid after the introduction of LMMHD power generation. The study utilizes a multi-dimensional model to evaluate the performance of the CBC enhanced by multi-stage LMMHD generators coupled with hydrocarbon fuel scramjet. The multi-stage mixing-separation LMMHD generator is proposed to decouple the void fraction of the MHD channel and the wall cooling process, and control the void fraction by change number of stages. The calculation result indicate that the void fraction significantly affects the overall power generation performance, including output power, performance boundary, etc. Increasing the void fraction is beneficial, and the optimal void fraction is 0.65. At the same Mach number, the fuel cooling capacity available to the system increases with the fuel equivalence ratio, resulting in higher total power output. The maximum Mach number for thermal protection of the combustor walls alone may surpass 9.5. For gas void fractions of 0.35/0.5/0.65, the maximum power generation reaches 182.8/167.1/156.9 kW, respectively. The novel system is compared with other advanced thermal-electricity conversion cycles under nearly the same conditions and demonstrated clear performance advantages.

Life prediction based on fatigue-environment damage under multiaxial thermo-mechanical loading

In this paper, the competition mechanism between protectiveness and harmfulness of oxidation, as well as the effects of cycle period, mean stress and temperature on the damage behavior of TA15 titanium alloy are revealed under multiaxial thermo-mechanical fatigue loading. Based on the damage mechanism, a high-temperature environmental damage model is proposed under multiaxial thermo-mechanical fatigue loading first, then a life prediction method is developed by combining a multiaxial fatigue damage model. The experimental verification results under uniaxial and multiaxial thermo-mechanical fatigue loadings showed that almost all of the prediction errors are within a factor of 2.

Small scale CO2 based trigeneration plants in heat recovery applications: A case study for residential sector in northern Italy

This study investigates the potential of trigeneration systems utilizing CO2-based power cycles to harness high-temperature excess heat. Various CO2-based cycles are proposed, comprising pure CO2 and CO2-mixture, emphasizing integration into district heating and cooling networks. Given the non-isothermal heat rejection of CO2-based cycles, performance maps for absorption chillers at different thermal levels and temperature drop of the heat source are generated. These maps are beneficial not only for the current study but also for generic applications. Various cycle layouts are studied, employing strategies to maximize overall electrical efficiency, electrical power output, or thermal production, starting from available high-grade heat above 500 °C. Depending on the specific cycle layout and strategy, the optimal cycle-thermal user coupling is evaluated. The economic and environmental viability of the proposed solution is evaluated in comparison to an existing case-study in northern Italy where the exhaust gases of 10 MWel gas turbines are currently exploited for district heating purposes and centralized vapour-compression chillers meet the residential cooling demand. Compared to the case-study, the adoption of a simple recuperative CO2-mixture bottoming cycle, at a minimum cycle temperature of 70 °C, allows not only a primary energy saving of 16 % but also an 8 % reduction of levelized cost of electricity.

Research on Friction Performance of Friction Stir Welding Tools Based on Non-Smooth Structure.

In this study, based on the principles of bionics, we fabricated a bionic non-smooth concave pit structure on the shoulders of friction stir welding tools and detected the thermal cycling curve, downforce, and torque of the tool in the welding process. We tested the wear loss weight and analyzed the surface morphology of the shoulder surfaces after welding for 200 m. This study found that as the distance between the concave pits decreased and the number of concave pits increased, the maximum downforce, torque, and temperature in the welding process showed a decreasing trend. As the speed increased, no matter how the tool structure changed, the downforce and torque decreased, while the peak thermal cycle temperature increased. The experimental welding results show that the wear loss weight of the non-smooth structure tool significantly reduced. The lowest wear loss weight of the tool with a concave pit interval of 1.125 mm was only 0.1529 g, which is 27% lower than that of the conventional tool. Our observations of the surface morphology of the tool shoulder after welding showed that the amount of aluminum swarf on the tool shoulder of the welding tool gradually declined with the increasing density of the uneven pits. The lowest number of aluminum chips adhered to a welding tool with a pit distance of 1.125 mm. Therefore, friction stir welding tools with biomimetic structures have better wear resistance and adhesion resistance.

A technique for separating the impact of cycle aging and temperature on Li-ion battery capacity

Reduction of battery capacity is a well-known symptom of aging, making it a universally accepted indicator of the state of health. Capacity also significantly depends on temperature, therefore, separating the effect of temperature from that due to aging has utmost important for a proper state of health assessment. However, according to the latest literature, there is a lack of information about how the temperature dependency of capacity changes with battery aging. In this respect, the study presented in this paper is based on an experimental campaign aimed at measuring battery capacity at different temperatures and cycling levels. Starting from the obtained results, an analytical model describing how the variation law of battery capacity with temperature is affected by cycling was proposed and validated. The achieved accuracy is better than 0.6 % for all the considered operating conditions.

Experiment investigation for interconnected effects of driving cycle and ambient temperature on bidirectional energy flows in an electric sport utility vehicle

The constrained driving range has emerged as a pivotal quandary impeding the advancement of electric sport utility vehicles (ESUVs). In this study, energy flow tests were executed on an ESUV to investigate interconnected effects of driving cycle and ambient temperature on bidirectional energy flows throughout the entire driving range. The results reveal that air conditioner singularly imposes a substantial surge in energy consumption at high-temperature settings. Notably, energy utilization efficiency (ηuti) reaches its zenith under Fixed speed cycle at room temperature (FSR_R) and energy recovery efficiency (ηrec) attains its peak under World Light Vehicle Test Cycle at room temperature (WLTC_R). Nevertheless, ηuti and ηrec attain their acme at room temperature and reach their nadir under low-temperature conditions, regardless of the specific driving cycle employed. Battery average temperature exhibits an ascending trajectory at room temperature and displays cyclic fluctuations at high temperature, while first increasing rapidly and then decreasing gradually in low-temperature ambient. Battery output energy per cycle initially decreases and eventually stabilizes with increasing the cycle count, and the battery recovery energy shows an initial upward trend followed by a stabilization phase. These findings provide empirical substantiation and prescriptive insights for mitigating energy consumption and enhancing driving range of ESUVs.

Time-of-day does not impact skeletal muscle contractile function, fatigability, or contraction-stimulated glucose uptake

Time-of-day impacts different aspects of mammalian physiology, such as the sleep/wake cycle, blood pressure, and body temperature. These time-of-day changes, or “circadian cycles”, are regulated by a central clock in the central suprachiasmatic nucleus of the hypothalamus and peripheral clocks located in other tissues, such as the liver, heart, and skeletal muscle. Interestingly, a growing body of data suggests that exercise performance and capacity also vary by time-of-day, with chronobiological effects on skeletal muscle metabolism and contractile function (i.e., force production) being proposed as important mediators. However, to date, no studies have specifically investigated the effect of time-of-day on skeletal muscle contractile function or glucose metabolism. The objective of this work was to assess ex vivo skeletal muscle contractile function, fatigability, and contraction-stimulated glucose uptake in the extensor digitorum longus (EDL) and soleus from 13-week-old female C57BL/6NJ mice at four different times-of-day (Light cycle time-points: Zeitgeber Time [ZT] ZT1 and ZT7; Dark cycle time-points: ZT13 and ZT19). We used an ex vivo approach as it allowed us to study skeletal muscle in isolation, and thus, independent of other factors that might influence contractile function or glucose metabolism (e.g., nerve function, humoral factors, etc.). We hypothesized that skeletal muscle contractile function, fatigability and contraction-stimulated glucose uptake would not be different by time-of-day. To control for meal-timing, mice were orally gavaged with dextrose (2 g/kg) and then fasted (3 hours) before contractile testing, which consisted of a force-frequency test (1-120 Hz, 0.3 ms pulse, 35 volts; 300 ms and 400 ms train for EDL and soleus, respectively) followed by a 15 minute fatigue test in which the muscles were repeatedly stimulated (EDL: 100 Hz stimulation every 15 seconds; Soleus: 30 Hz stimulation every 2 seconds). Glucose uptake was measured during the fatigue test using the [3H]-2-deoxyglucose (2DOG) uptake approach, with the contralateral muscle being the rested control. Significantly, contractile function, including peak twitch tension and maximal tetanic tension (EDL — ZT1: 281±13; ZT7: 300±21; ZT13: 261±28; ZT19: 280±40 kPa, P = 0.7661, one-way ANOVA; Soleus — ZT1: 117±16; ZT7: 115±18; ZT13: 117±11; ZT19: 111±10 kPa, P = 0.9923, one-way ANOVA) were not different by time-of-day. Similarly, fatigability, as measured as the tension·time integral during the 15 min fatigue test was not different by time-of-day (EDL — ZT1: 640±89; ZT7: 686±92; ZT13: 708±110; ZT19: 683±142 kPa·min, P = 0.9803, one-way ANOVA; Soleus — ZT1: 245±42; ZT7: 261±35; ZT13: 200±41; ZT19: 244±34 kPa·min, P = 0.7019, one-way ANOVA). Finally, while contraction significantly increased 2DOG uptake above basal by ~1.6-fold and ~1.8-fold in the soleus and EDL, respectively, this increase was not different by time-of-day. Taken together, these results demonstrate that time-of-day does not impact skeletal muscle contractile function, fatigability, or contraction-stimulated glucose uptake, regardless of muscle type. By extension, skeletal muscle, per se, is unlikely to be a contributing factor to the documented effects of time-of-day on whole-body exercise performance. This was funded by the UC San Diego Medical Scientist Training Program and NIH R21 AG067495. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Performance Analysis of Wave Rotor Combustor Integration into Baseline Engines: A Comparative Study of Pressure-Gain and Work Cycles

This study presents two concepts for integrating a wave rotor combustor (WRC) into a baseline engine: the wave rotor pressure-gain cycle (WRPGC) and the wave rotor work cycle (WRWC). Performance parameters were calculated under different thermodynamic cycles, and a comparative analysis of the thermodynamic cycles was conducted, considering both the ideal- and actual-loss conditions. Furthermore, the impact of the WRC precompression ratio, turbine inlet temperature, and fixed peak cycle temperature on the thermodynamic-cycle performance was investigated. The results indicate that embedding a WRC into a baseline engine with a compressor pressure ratio higher than 24.0 does not lead to an improvement in the thermal efficiency. However, under a baseline engine pressure ratio of 3.6, the actual-loss WRC cycle achieves efficiency improvements of 40.5% and 49.5% in the WRPGC and WRWC, respectively, compared to the baseline engine cycle. Increasing the wave rotor precompression ratio or the turbine inlet temperature ratio results in greater performance improvements for the WRWC compared to the WRPGC. When the peak cycle temperature of the wave rotor is fixed, there exists a narrow pressure ratio range wherein the WRPGC outperforms the WRWC. Therefore, the WRPGC is more suitable for embedment in baseline engines with lower pressure ratios.

Mid-Deep Circulation in the Western South China Sea and the Impacts of the Central Depression Belt and Complex Topography

As a key component of meridional overturning circulation, mid-deep circulation plays a crucial role in the vertical and meridional distribution of heat. However, due to a lack of observation data, current knowledge of the dynamics of mid-deep circulation currents moving through basin boundaries and complicated seabed topographies is severely limited. In this study, we combined oceanic observation data, bathymetric data, and numerical modeling of the northwest continental margin of the South China Sea to investigate (i) the main features of mid-deep circulation currents traveling through the central depression belt and (ii) how atmospheric-forcing (winds) mesoscale oceanic processes such as eddies and current–topography interactions modulate the mid-deep circulation patterns. Comprehensive results suggest that the convergence of different water masses and current–topography interactions take primary responsibility for the generation of instability and enhanced mixing within the central depression belt. By contrast, winds and mesoscale eddies have limited influence on the development of local circulation patterns at mid-deep depths (&gt;400 m). This study emphasizes that the intensification and bifurcation of mid-deep circulation; specifically, those induced by a large depression belt morphology determine the local material cycle (temperature, salinity, etc.) and energy distribution. These findings provide insights for a better understanding of mid-deep circulation structures on the western boundary of ocean basins such as the South China Sea.

Thermodynamic performance of an innovative space nuclear Brayton cycle with S–N2O

The supercritical Brayton cycle system is renowned for its characteristics of elevated high-power density, compact structure, lightweight design, and extended operational lifespan, rendering it as a preeminent energy conversion approach for space nuclear power systems. Using nitrous oxide (N2O) as the working fluid in a supercritical Brayton cycle system enables heightened efficiencies at comparatively lower cycle temperatures. This study examined four distinct layout configurations, culminating in an in-depth analysis of their respective thermodynamic performances. Among the configurations analyzed, the newly proposed recompression Brayton cycle with partial cooling and heat recovery (RBC-PCHR) layout exhibited the best thermodynamic performance compared to other cycle configurations. This superiority can be principally attributed to augmented heat recovery procedures and reduced compression workloads. A detailed multi-objective optimization strategy is subsequently embarked upon, building upon the insights gained from the sensitivity analysis pertaining to the key operating parameters. The optimization outcomes show significant enhancements, with an increase of 1.37% in ηth and 32.18% in MBRU, along with a marginal decrease of 0.70% in ηex.

Risk factors and prediction model construction for peripherally inserted central catheter-related infections

ObjectiveTo establish a predictive modeling for the risk of bloodstream infection associated with peripherally inserted central catheter (PICC). MethodsPatients receiving PICC treatment in Shenzhen People's Hospital from June 2020 to December 2020 were retrospectively enrolled and divided into the infection group and the non-infection group according to the presence and absence of PICC-related infections. Then, relevant clinical information of patients was collected and the predictors of PICC-related infection were screened by the least absolute shrinkage and selection operator regression (LASSO) model. Besides, multivariate logistic regression was used to analyze the influencing factors of PICC-related infection, A nomogram was constructed based on the results of the multivariate analysis. Ultimately, a receiver operating characteristic (ROC) curve was plotted to analyze the application value of influencing factors to predict PICC-related infections. ResultsA total of 505 patients were included, including 75 patients with PICC-related infections (14.85%). The main pathogen was gram-positive cocci. The predictors screened by LASSO included age >60 years, catheter movement, catheter maintenance cycle, insertion technique, immune function, complications, and body temperature ≥37.2 °C before PICC placement. Multivariate logistic regression analysis showed that independent risk factors of infections related to PICC included age >60 years [odds ratio (OR) = 1.722; 95% confidence interval (CI) = 1.312–3.579; P = 0.006], catheter movement (OR = 1.313; 95% CI = 1.119–3.240; P = 0.014), catheter maintenance cycle >7 days (OR = 2.199; 95% CI = 1.677–4.653; P = 0.000), direct insertion (OR = 1.036; 95% CI = 1.019–2.743; P = 0.000), poor immune function (OR = 2.322; 95% CI = 2.012–4.579; P = 0.000), complications (OR = 1.611; 95% CI = 1.133–3.454; P = 0.019), and body temperature ≥37.2 °C before PICC placement (OR = 1.713; 95% CI = 1.172–3.654; P = 0.012). Besides, the area under the ROC curve was 0.889. ConclusionPICC-related infections are associated with factors such as age >60 years, catheter movement, catheter maintenance cycle, insertion technique, immune function, complications, and body temperature ≥37.2 °C before PICC placement. Additionally, the LASSO model is moderately predictive for predicting the occurrence of PICC-related infections.