Downstream Heat Research Articles

Unveiling the impact of SUMOylation at K298 site of heat shock factor 1 on glioblastoma malignant progression

BackgroundGlioblastoma (GBM) poses a significant medical challenge due to its aggressive nature and poor prognosis. Mitochondrial unfolded protein response (UPRmt) and the heat shock factor 1 (HSF1) pathway play crucial roles in GBM pathogenesis. Post-translational modifications, such as SUMOylation, regulate the mechanism of action of HSF1 and may influence the progression of GBM. Understanding the interplay between SUMOylation-modified HSF1 and GBM pathophysiology is essential for developing targeted therapies. MethodsWe conducted a comprehensive investigation using cellular, molecular, and in vivo techniques. Cell culture experiments involved establishing stable cell lines, protein extraction, Western blotting, co-immunoprecipitation, and immunofluorescence analysis. Mass spectrometry was utilized for protein interaction studies. Computational modeling techniques were employed for protein structure analysis. Plasmid construction and lentiviral transfection facilitated the manipulation of HSF1 SUMOylation. In vivo studies employed xenograft models for tumor growth assessment. ResultsOur research findings indicate that HSF1 primarily undergoes SUMOylation at the lysine residue K298, enhancing its nuclear translocation, stability, and downstream heat shock protein expression, while having no effect on its trimer conformation. SUMOylated HSF1 promoted the UPRmt pathway, leading to increased GBM cell proliferation, migration, invasion, and reduced apoptosis. In vivo studies have confirmed that SUMOylation of HSF1 enhances its oncogenic effect in promoting tumor growth in GBM xenograft models. ConclusionThis study elucidates the significance of SUMOylation modification of HSF1 in driving GBM progression. Targeting SUMOylated HSF1 may offer a novel therapeutic approach for GBM treatment. Further investigation into the specific molecular mechanisms influenced by SUMOylated HSF1 is warranted for the development of effective targeted therapies to improve outcomes for GBM patients.

Innovative configurations for heat sink integrated with piezoelectric fans

Piezoelectric (PE) fans are gradually replacing conventional axial flow fans in the field of heat dissipation for microelectronics due to small size and high efficiency. However, the flow characteristic of PE fans was seldom considered when arranging heat sink fins, which could not utilize the fans’ advantages. Here, the design of fin arrangement based on the transient flow field generated by the vibration of dual PE fans in the channel was calculated and analyzed by CFD simulation and dynamic grid technology. Four zones with different flow field characteristics were found: Zones 1 and 4 which located inlet and outlet of the channel were Parallel flow zone. Zone 2 with vortices corresponds to the area ranges from the waist of blades to middle section of the channel was Multiple vortices flow zone. Zone 3 with high-speed vortices and jet flows corresponds to the area ranges from middle section of the channel to halfway downstream of blades region was Diffuse flow zone. Innovative configurations of heat sinks where fins arranged at the inlet and surrounding blades were designed according to the flow field characteristics: the loss of high-speed airflow to the inlet was prevented effectively and heat dissipation in the downstream heat sinks was dispersed by fins arranging in Parallel flow zone and Multiple vortices flow zone. The development and merging of high-speed vortices were strengthened by the inhomogeneous pin-fins arranging in Diffuse flow zone. The optimal coordination between the velocity field and the temperature gradient field among innovative configurations was found based on the field coordination analysis. Heat transfer performance was enhanced by new designs where the average temperature compared to conventional heat sink with PE fans was reduced by 16.7°. Our work provided a new fins arrangement to achieve uniform temperature distribution and high heat transfer performance for heat sink integrated with PE fans and would benefit the application in thermal management of high power devices integrated with PE fans.

Forecasting the flame geometry and ground received radiative heat fluxes of two parallel adjacent fires of hydrocarbon fuel with crosswinds

Radiative heat transfer in fires is a critical parameter and a key aspect of gas storage and fire prevention design. In this study, the flame geometric scale characteristics and ground-received radiative heat fluxes from two parallel adjacent hydrocarbon fuel fires with crosswinds were examined. The separation distance between the two parallel flames, crosswind speed, and heat release rates were considered. The experimental results indicated that the flame tilt angle of the two parallel flames increased with increasing crosswinds. The horizontal flame length scale of the two adjacent parallel flames first increased with the crosswind until a critical point was reached, followed by a fluctuation with a further increase in the wind speed. To further quantify this flame phenomenon, a physical model of the flame interaction between two parallel fires under the effects of crosswinds was proposed. The model analyzed major factors affecting the geometrical parameters of the flame, including the inertial force caused by the crosswind, thermal buoyancy from flame combustion, and the interaction and separation distance between the two fires. Additionally, correlations between the flame tilt angle and the horizontal flame length scale of the two adjacent flames were proposed. It was also demonstrated that the ground-received downstream radiative heat fluxes were the dominant parameters determining flame spread. Based on the assumption of the flame geometry of two adjacent parallel fires, the viewing factor was revised, and the relationship between the position of the radiant point and the horizontal length of the flame was considered in the flame model. Furthermore, based on the updated viewing factor of two parallel adjacent flames, a prediction model of ground-received radiative heat fluxes was proposed, which successfully estimated the variation of ground-received downstream radiative heat flux profiles along the centerline of the two parallel flames under crosswind conditions. This estimation is crucial for future fire research, particularly cross-wind-related experiments.

The heat transfer enhancement mechanism of W-shaped micro-ribs on impingement cooling

In order to improve the performance of impingement cooling in turbine blades, W-shaped micro-ribs are arranged on the target surface to weaken the influence of cross-flow and generate longitudinal vortexes. The k-ω SST turbulence model is used for numerical simulation, and the mechanism of W-ribs on the enhancement of air impingement cooling performance and the influence of W-ribs geometry are studied. Under the condition of jet flow Reynolds number 4000 to 10000, based on the W-ribs with an angle α = 120°, width W = 0.1 mm and height H = 0.3 mm, the effects of angle (α = 90°, 120°, 150°, 180°), width (W = 0.05, 0.1, 0.2, 0.4 mm) and height (H = 1, 3, 4, 8 mm) on flow and heat transfer are investigated respectively. The results show that the W-ribs can separate the flow to both sides while generating longitudinal vortexes, which can reduce the influence of crossflow and enhance the sweep of the target surface to achieve the effect of enhancing heat transfer. α is the key factor affecting the generation of longitudinal vortex. W has little effect on the flow structure, but mainly affects the vorticity. H mainly affects the distribution of mass flow rate, which has a direct impact on the uniformity of upstream and downstream heat transfer. The W-ribs with α = 120°, W = 0.1 mm and H = 0.4 mm is recommended because of its excellent heat transfer performance and high comprehensive heat transfer performance, which are 39.7–48.9 % and 1.5–9.7 % higher than the smooth target surface, respectively.

Integrated Performance of a Modular Biomass Boiler With a Combined Heat and Power Industrial Rankine Cycle and Supplementary sCO2 Brayton Cycle

Abstract In this paper, the integrated performance of a modular biomass boiler with an existing industrial Rankine steam heat and power cycle and a supplementary supercritical-carbon dioxide (sCO2) Brayton cycle is analyzed. The aim is to leverage the high efficiency supplementary sCO2 cycle to increase net generation and energy efficiency from the existing biomass boiler. Two sCO2 heater configurations situated within the flue gas flow path are investigated, namely a single convective-dominant heater, and a dual heater configuration with a radiative and a convective heater. A quasi-steady-state 1D model was developed to simulate the integrated cycle, including detailed component characteristics for the Rankine and Brayton cycles. The model solves the mass, energy, momentum, and species balance equations. The system is analyzed for three cases: (i) the existing Rankine cycle without the sCO2 integration, (ii) with the single convective-dominant sCO2 heater configuration, and (iii) the dual sCO2 heater configuration. The results show the required rate of overfiring for the sCO2 configurations, with a 15.3% increase in fuel flowrate resulting in an additional 21.2% in net power output. The model quantifies the impact of the sCO2 heaters, with reduced heat uptakes for downstream boiler heat exchangers. Furnace water wall heat uptake increased due to overfiring, offsetting the reduced heat uptakes at downstream evaporative heat exchangers. The dual configuration has more impact on Rankine cycle operation due to the radiative sCO2 heater placement in front of the second superheater, absorbing some of the direct radiation from the furnace.

Global optimization strategy of prosumer data center system operation based on multi-agent deep reinforcement learning

The escalating issues of high energy consumption and carbon emissions in data centers (DCs) necessitate the optimization of system operations. However, early optimization strategies were overly simplistic and lacked automated updating and iterative capabilities. With the evolution of artificial intelligence (AI), researchers have applied deep reinforcement learning (DRL) algorithms to system operations. However, the optimization focus has been limited to the internal systems, lacking global optimization. In this paper, a global optimization control strategy based on the Dueling double-deep Q network (D3QN) and value decomposition network (VDN) algorithms is proposed to make the DCs system operate more closely with the upstream, midstream, and downstream. By adjusting battery charging/discharging capacity, computational workload, and waste heat utilization heating temperature global synergistic optimization is achieved. Compared with without optimization, renewable energy waste, operation cost, total electricity consumption, and grid electricity consumption are reduced by 18.37%, 9.78%, 4.01%, and 29.74%, respectively. Additionally, a detailed comparison between non-algorithmic optimization and algorithmic optimization is provided, offering valuable insights for substantial energy savings and emissions reduction in DCs. The results demonstrate the importance of fully exploring the interactive potential between upstream energy supply, midstream computational workload, and downstream waste heat recovery to achieve synergistic global optimization of “computing power", “thermal energy" and “electrical energy" for the sustainable and green development of DCs or other prosumer buildings.

Stability analysis of premixed flames with downstream heat gain

Pulsating instability is a kind of combustion intrinsic instability, that can affect the flammable limit and may couple with other processes to generate more complex combustion instability phenomena. Pulsating instability was found in the premixed flame of the double-flame partially premixed flame (PPF), in which the flame patterns change from stable to pulsating unstable, and to stable again as the equivalence ratio or stretch rate increases. To further investigate this phenomenon, a simpler model, stretched premixed flames with downstream heat gain, is analyzed by the asymptotic expansion method in this paper. The downstream heat gain inhibits the steady extinction of stretched premixed flames with a large Zeldovich number. The stability of premixed flames changes in the zero-limit mode, two-limits mode and one-limit mode sequentially as the Zeldovich number increases. The zero-limit mode represents the premixed flame is stable for all stretch rates. The two-limit mode and one-limit represent the premixed flame changes in the pattern of stable-pulsating-stable and pulsating-stable as the stretch rate increases, respectively. The downstream heat gain suppresses the pulsating instability to yield the stable region at the large stretch rate and large Zeldovich number. The influence of other factors, including the Lewis number, the downstream temperature and the downstream boundary position are also discussed. The current theoretical method is also applied to the extracted parameters from numerical calculations of hydrogen/air double-flame PPF. A qualitative similarity is found between the theoretical results and numerical results.

The Asymptotic Structure of Strained Chain-Branching Premixed Flames Under Nonadiabatic Conditions

ABSTRACT The present paper, which investigates the chain-branching premixed-flame dynamics under nonadiabatic conditions, is the third and final contribution to a series of studies on premixed flames with the modified Zel’dovich-Liñán two-step mechanism under the three most prevailing physical influences, namely (i) flame stretch, (ii) differential diffusion, and (iii) heat loss to or gain from the flame downstream. Asymptotic analysis for the chain-branching premixed-flame structure is carried out within the framework of the intermediate recombination regime, in which the chain-recombination layer with a characteristic thickness of O ( β − 1 / 2 ) is asymptotically thicker than the inner chain-branching layer but thinner than the outer convective-diffusive layer. The combustion characteristics are presented by the M – Δ plots, where the specific reaction intensity M is a measure of the reaction intensity and the reduced recombination Damköhler number Δ is a measure of the inverse of the flame stretch. The M – Δ plots are found to exhibit a striking resemblance to the AEA counterparts of Libby and Williams (1983), in that the S-shaped M – Δ curves emerge for sufficiently large downstream heat losses. The Damköhler number ratio D I / D II is found to be another key parameter controlling the chain-branching flame dynamics. The greater D I / D II , the slower the recombination reaction and the thicker the recombination layer tends to be, which results in a reduced overall nonlinearity for the Zel’dovich-Liñán two-step mechanism. Consequently, abrupt extinction is less likely observable in the much slower recombination regime. Combining with the results of the previous two papers by the authors, the overall combustion characteristics of strained chain-branching premixed flames with the Zel’dovich-Liñán two-step kinetics is found to be in qualitatively good agreement with that of one-step AEA, unless the recombination step is too slow or too fast to be reasonably described by the intermediate recombination regime.

HSFA3 functions as a positive regulator of HSFA2a to enhance thermotolerance in perennial ryegrass

Perennial ryegrass (Lolium perenne) is a widely used cool season turfgrass with outstanding turf quality and grazing tolerance. High temperature is the key factor restricting the distribution of perennial ryegrass in temperate and sub-tropic regions. In this study, we found that one HEAT SHCOK TRANSCRIPTION FACOTR (HSF) class A gene from perennial ryegrass, LpHSFA3, was highly induced by heat stress. LpHSFA3 is localized in nucleus and functions as a transcription factor. Ectopic overexpression of LpHSFA3 in Arabidopsis improved thermotolerance and rescued heat sensitive deficiency of athsfa3 mutant. Overexpression of LpHSFA3 in perennial ryegrass enhanced heat tolerance and increased survival rate in summer season as evidenced by decreased EL and MDA, increased number of green leaves and total chlorophyll content. LpHSFA3 binds to the HSE region in LpHSFA2a promoter to constitutively activate the expression of LpHSFA2a and downstream heat stress responsive genes. Ectopic overexpression of LpHSFA2a consequently rescued thermal sensitivity of athsfa3 mutant and enhanced thermotolerance of athsfa2 mutant. Perennial ryegrass protoplasts with overexpression of LpHSFA3 and LpHSFA2a exhibited induction of similar subsets of heat responsive genes. These results indicated that transcription factor LpHSFA3 functions as positive regulator of LpHSFA2a to improve thermotolerance of perennial ryegrass, providing further evidence to understand the regulatory networks of plant heat stress response.

Interaction between huntingtin exon 1 and HEAT repeat structure probed by chimeric model proteins.

Huntington disease (HD) is associated with aggregation of huntingtin (HTT) protein containing over 35 continuous Q residues within the N-terminal exon 1 encoded region. The C-terminal of the HTT protein consists mainly of HEAT repeat structure which serves as a scaffold for multiple cellular activities. Structural and biochemical analysis of the intact HTT protein has been hampered by its huge size (~300 kDa) and most in vitro studies to date have focused on the properties of the exon 1 region. To explore the interaction between HTT exon 1 and the HEAT repeat structure, we constructed chimeric proteins containing the N-terminal HTT exon 1 region and the HEAT repeat protein PR65/A. The results indicate that HTT exon 1 slightly destabilizes the downstream HEAT repeat structure and endows the HEAT repeat structure with more conformational flexibility. Wild-type and pathological lengths of polyQ did not show differences in the interaction between HTT exon 1 and the HEAT repeats. With the C-terminal fusion of PR65/A, HTT exon 1 containing pathological lengths of polyQ could still form amyloid fibrils, but the higher-order architecture of fibrils and kinetics of fibril formation were affected by the C-terminal fusion of HEAT repeats. This indicates that interaction between HTT exon 1 and HEAT repeat structure is compatible with both normal function of HTT protein and the pathogenesis of HD, and this study provides a potential model for further exploration.

Experimental study of downstream local heat flux of pool fires under relatively strong cross flows

Pool fire is the common form of combustion posing hazard to surroundings by thermal heat transfer. The local heat flux of pool fire under relatively small cross flow has been widely studied. However, none work investigates the influence of relatively strong cross flow to the local heat flux of pool fires. In this study, experiments are carried out to reveal the effect of strong cross flow on the downstream heat flux distributions of pool fires. Four square quartz sand boxes with the side lengths of 8 cm, 10 cm, 15 cm, and 20 cm are applied to simulate the pool fires. The cross flow speed ranges from 0 to 5.0 m/s. Eight local heat flux gauges are aligned downstream with 6 cm interval. In still air or when the flame base drag is smaller than the distance (6 cm) between the closest heat gauge and downstream pool rim, the heat flux decreases monotonically with the downstream distance. For other conditions, the local heat flux firstly increases then decreases with the downstream distance. And the location of peak local heat flux is the same as the flame base drag length. For a given pool size and heat release rate, the evolution of local heat flux with cross flow speed is complicated and shows three trends. Local heat flux is determined by the flame base drag representing the influence of pool dimension, cross flow speed, heat release rate and side entrainment, as well as downstream distance. Two regions of local heat flux are observed based on the different physics of heat transfer. Correlations are obtained for the two regions respectively and agree well with the experimental data.

Experimental study on air impinging jet for effective cooling of multiple protruding heat sources

Air Impinging Jet is an effective cooling method for various applications, ensuring optimal performance and reliability of heat-generation systems. In the present work, a novel technique of cooling discrete protruding heat sources mounted in a rectangular channel by using a double air jet is introduced experimentally. A constant and uniform heat flux is produced from protruding heat source surfaces where the bottom and the upper channel walls are insulated. The effects of various parameters on the heat source cooling performance such as the Nusselt number for single and double air jets are obtained. Various parameters such as the air Reynolds number, aspect ratio, double jet position ratio, and jet inclination angle are investigated. The results show that those parameters effectively affect the average temperatures and the standard deviation of all protruding heat sources. It is indicated that the maximum value of the average Nu number occurs at the heat source just underneath the impinging air jet compared to other downstream heat sources. The highest average Nu is achieved at a position ratio of 3/7 and an inclination angle of 10o. The cooling system accomplishes an acceptable Nu and temperature uniform distribution for a position ratio of 4/7 compared to the other position ratios. The improved performance and longevity of heat sources are achieved by the innovative double-air jet method, which archives a consistent temperature distribution for all projecting heat sources.

Experimental investigation on the effects of a mesh in the downstream region of a combustion-driven Rijke tube on self-excited thermoacoustic oscillations

Self-excited thermoacoustic oscillations are undesirable in most combustion systems due to their negative influence on combustion efficiency and structural vibration. Nonlinear thermoacoustic oscillations driven by combustion can be sensitive to changes in the heat and flow conditions. Therefore, a comprehensive study on self-excited thermoacoustic oscillations was conducted to investigate the effect of incorporating a woven mesh with varying mesh numbers and positions into the downstream region of a Rijke tube. This study determined system frequency and amplitude response and revealed dynamic properties of the system by applying recurrence analysis. To obtain temperature distributions, a thermal imaging system was employed, comprising a short wavelength infrared (SWIR) camera for the mesh and a long wavelength infrared (LWIR) camera for the tube wall. A high-speed schlieren imaging system was utilised for visualising heat and flow conditions at the tube end. The study demonstrated the effect of including a mesh in changing the oscillation eigenfrequency, suppressing the oscillation amplitude by up to 50 % and influencing the system dynamics. Higher mesh number demonstrated greater effectiveness. The captured thermal and schlieren images clearly evidenced the mesh’s significant influence on the downstream heat and flow conditions. The insights gained from this work provide a potential control method of self-excited, nonlinear thermoacoustic oscillations.

Integrated optimization for utilizing iron and steel industry’s waste heat with urban heating based on exergy analysis

A substantial quantity of waste heat resources generated in iron and steel manufacturing process (ISMP) can fulfill certain demand for urban heating. However, the waste heat utilization level of different iron and steel enterprises varies a lot and few studies have combined the upstream enterprise’s production with downstream waste heat utilization for discussion. By establishing an optimization model based on material balance, thermodynamic laws and reaction mechanism of the ISMP, this study firstly obtain the minimum exergy loss and the corresponding production cost ＆ exergy efficiency. The total exergy loss of ISMP is reduced from 8413.19 MJ/t-MS to 7669.27 MJ/t-MS. The exergy efficiency of the whole process is increased from 63.75 % to 65.46 % and the total waste heat potential reaches 1471.25 MJ/t-MS. It is found that coke ratio, air leakage rate, scrap steel ratio, etc. have great impact on exergy loss of ISMP. Then, the optimization and evaluation of the waste heat utilization are carried out by establishing models with taking urban heating into consideration. The available external heat supply is 813.15 to 853.55 MJ/t-MS and the enterprise's heating load can reach 229.23–251.47 MW, which allow to supply heat for an area of 5.46–5.93 million m2. Finally, the problem of waste heat instability in the heating process is briefly discussed and some solution strategies are proposed to overcome this defect.

Alternative splicing of TaHSFA6e modulates heat shock protein-mediated translational regulation in response to heat stress in wheat.

Heat stress greatly threatens crop production. Plants have evolved multiple adaptive mechanisms, including alternative splicing, that allow them to withstand this stress. However, how alternative splicing contributes to heat stress responses in wheat (Triticum aestivum) is unclear. We reveal that the heat shock transcription factor gene TaHSFA6e is alternatively spliced in response to heat stress. TaHSFA6e generates two major functional transcripts: TaHSFA6e-II and TaHSFA6e-III. TaHSFA6e-III enhances the transcriptional activity of three downstream heat shock protein 70 (TaHSP70) genes to a greater extent than does TaHSFA6e-II. Further investigation reveals that the enhanced transcriptional activity of TaHSFA6e-III is due to a 14-amino acid peptide at its C-terminus, which arises from alternative splicing and is predicted to form an amphipathic helix. Results show that knockout of TaHSFA6e or TaHSP70s increases heat sensitivity in wheat. Moreover, TaHSP70s are localized in stress granule following exposure to heat stress and are involved in regulating stress granule disassembly and translation re-initiation upon stress relief. Polysome profiling analysis confirms that the translational efficiency of stress granule stored mRNAs is lower at the recovery stage in Tahsp70s mutants than in the wild types. Our finding provides insight into the molecular mechanisms by which alternative splicing improves the thermotolerance in wheat.

Molten carbonate fuel cell integrated hybrid system for clean and efficient power generation

Thermo-economic and environmental analyses of a hybrid power generation system were performed in this study, which included a biomass steam gasifier, an indirect heated air turbine unit, carbon dioxide separation, capture, and sequestration using a molten carbonate fuel cell, downstream waste heat recovery via organic Rankine cycle, and steam Rankine cycle. Furthermore, multi-objective optimization was performed using response surface methodology to determine the operating state at which the system delivers the highest value of exergy efficiency while also having the lowest cost of electricity. It has been found that the conceptualized system delivers its optimum output when the air compressor operates at a pressure ratio of 9.41, the temperature at the inlet of the air turbine is 1100 °C, the molten carbonate fuel cell operates at 1500 A⋅m−2 current density with 80% fuel utilization, and the heat recovery steam generator pressure is 150 bar. The optimized values of the cost of electricity and exergy efficiency have been found to be 0.0993 $/kWh and 47.46%, respectively. At the optimum condition, the plant generates 1.3 MW power with an energy efficiency of 54.5%, capturing 5052.58 tonnes of CO2 in a year, producing $0.758 million in environmental benefit. It has been found from this study that the optimized hybrid power system yields better exergy efficiency and unit cost of electricity in comparison to the existing conventional biomass-based plants available in the literature.

Heat Shock Protein 27 Is Involved in the Bioactive Glass Induced Osteogenic Response of Human Mesenchymal Stem Cells.

Bioactive glass (BaG) materials are increasingly used in clinics, but their regulatory mechanisms on osteogenic differentiation remain understudied. In this study, we elucidated the currently unknown role of the p38 MAPK downstream target heat shock protein 27 (HSP27), in the osteogenic commitment of human mesenchymal stem cells (hMSCs), derived from adipose tissue (hASCs) and bone marrow (hBMSCs). Osteogenesis was induced with ionic extract of an experimental BaG in osteogenic medium (OM). Our results showed that BaG OM induced fast osteogenesis of hASCs and hBMSCs, demonstrated by enhanced alkaline phosphatase (ALP) activity, production of extracellular matrix protein collagen type I, and matrix mineralization. BaG OM stimulated early and transient activation of p38/HSP27 signaling by phosphorylation in hMSCs. Inhibition of HSP27 phosphorylation with SB202190 reduced the ALP activity, mineralization, and collagen type I production induced by BaG OM. Furthermore, the reduced pHSP27 protein by SB202190 corresponded to a reduced F-actin intensity of hMSCs. The phosphorylation of HSP27 allowed its co-localization with the cytoskeleton. In terminally differentiated cells, however, pHSP27 was found diffusely in the cytoplasm. This study provides the first evidence that HSP27 is involved in hMSC osteogenesis induced with the ionic dissolution products of BaG. Our results indicate that HSP27 phosphorylation plays a role in the osteogenic commitment of hMSCs, possibly through the interaction with the cytoskeleton.

Prenatal LPS Exposure Promotes Allergic Airway Inflammation via Long Coding RNA NONMMUT033452.2, and Protein Binding Partner, Eef1D.

Epidemiological surveys indicate that intrauterine inflammation increases the risk of asthma in offspring. However, the underlying mechanisms remain largely unknown. Previous studies in BALB/c and C57BL/6 mice showed that prenatal exposure to endotoxins prevented allergic airway inflammation in offspring, which is inconsistent with most clinical observations. In this study, we found that prenatal LPS exposure increased airway resistance and total exfoliated cell counts, eosinophils, and IL-4 concentrations in BAL fluid of ovalbumin-sensitized Institute of Cancer Research (ICR) mice. Importantly, long noncoding RNA (lncRNA) NONMMUT033452.2 was upregulated in the lungs of LPS-exposed ICR offspring. Fluorescence in situ hybridization and cytoplasmic and nuclear fraction analyses revealed that this lncRNA was distributed in both the nuclei and cytoplasm of lung and airway epithelial cells, smooth muscle cells, and fibroblasts. Intranasal administration of NONMMUT033452.2 siRNA markedly alleviated allergic airway inflammation in ovalbumin-sensitized ICR mice. In vitro functional experiments demonstrated that overexpression of NONMMUT033452.2 inhibited the proliferation of lung and bronchiolar epithelial cells and promoted oxidative stress. RNA pull-down assays proved that NONMMUT033452.2 could directly bind Eef1D (eukaryotic translation elongation factor 1 delta). Overexpression of NONMMUT033452.2 induced the redistribution of Eef1D and substantially inhibited the expression of its downstream heat shock genes. NONMMUT033452.2 was also involved in the modulation of IL-1, IL-12, and some key molecules related to asthma, including Npr3 (natriuretic peptide receptor 3), Rac1 (Rac family small GTPase 1), and Nr4a3 (nuclear receptor subfamily 4, group A, member 3). Furthermore, the human lncRNA NONHSAT078603.2 was identified as a functional homolog of NONMMUT033452.2. These findings provide new insight into the pathogenic mechanism underlying asthma development.

Study on the heat transfer enhancement of self-excited oscillating pulsating flow by the boundary vortex group

In this work, the self-excited oscillating pulsating circular pipe is the object of study. Based on the flow evolution characteristics of the boundary layer and vortex, the mechanism of enhanced heat transfer by self-excited oscillating pulsating flow is investigated. Moreover, a vital flow structure, the boundary vortex ring (BVR for short), is proposed. The study results show that the vortex evolution within the shear layer inside the self-excited oscillating pulsating chamber has an important influence on the formation of the downstream boundary vortex ring. Both have the same period but different phases. The boundary vortex group formed by the BVR is distributed at intervals in the pipe, and its role in promoting fluid flow increases first and then decreases. At the same time, the strength of the central mainstream area is gradually strengthened. The boundary vortex group's flow state determines the downstream pipe's heat transfer characteristics. The low-velocity zone on both sides determines the position of the heat transfer coefficient enhancement, and the central vorticity determines the amplitude of the enhancement. The boundary vortex group with a complete structure can effectively promote heat transfer, while the boundary vortex group with an incomplete structure can suppress heat transfer. The time-averaged boundary layer thickness increase ratio δ′ and the time-averaged equal diameter circular tube performance evaluation index ηT provide the fundamental indexes for designing and optimizing variable cross section heat transfer circular tubes. Furthermore, the heat transfer coefficient of the tube wall varies synchronously with the thickness of the boundary layer.

ERF49 mediates brassinosteroid regulation of heat stress tolerance in Arabidopsis thaliana

BackgroundHeat stress is a major abiotic stress affecting the growth and development of plants, including crop species. Plants have evolved various adaptive strategies to help them survive heat stress, including maintaining membrane stability, encoding heat shock proteins (HSPs) and ROS-scavenging enzymes, and inducing molecular chaperone signaling. Brassinosteroids (BRs) are phytohormones that regulate various aspects of plant development, which have been implicated also in plant responses to heat stress, and resistance to heat in Arabidopsis thaliana is enhanced by adding exogenous BR. Brassinazole resistant 1 (BZR1), a transcription factor and positive regulator of BR signal, controls plant growth and development by directly regulating downstream target genes. However, the molecular mechanism at the basis of BR-mediated heat stress response is poorly understood. Here, we report the identification of a new factor critical for BR-regulated heat stress tolerance.ResultsWe identified ERF49 in a genetic screen for proteins required for BR-regulated gene expression. We found that ERF49 is the direct target gene of BZR1 and that overexpressing ERF49 enhanced sensitivity of transgenic plants to heat stress. The transcription levels of heat shock factor HSFA2, heat stress-inducible gene DREB2A, and three heat shock protein (HSP) were significantly reduced under heat stress in ERF49-overexpressed transgenic plants. Transcriptional activity analysis in protoplast revealed that BZR1 inhibits ERF49 expression by binding to the promoter of ERF49. Our genetic analysis showed that dominant gain-of-function brassinazole resistant 1-1D mutant (bzr1-1D) exhibited lower sensitivity to heat stress compared with wild-type. Expressing ERF49-SRDX (a dominant repressor reporter of ERF49) in bzr1-1D significantly decreased the sensitivity of ERF49-SRDX/bzr1-1D transgenic plants to heat stress compared to bzr1-1D.ConclusionsOur data provide clear evidence that BR increases thermotolerance of plants by repressing the expression of ERF49 through BZR1, and this process is dependent on the expression of downstream heat stress-inducible genes. Taken together, our work reveals a novel molecular mechanism mediating plant response to high temperature stress.