The regulation of ferrocene-based catalysts on heat transfer in highpressure combustion of ammonium perchlorate/hydroxyl-terminated polybutadiene/aluminum composite propellants

The regulation of the burning rate pressure exponent for the ammonium perchlorate/hydroxylterminated polybutadiene/aluminum(AP/HTPB/Al)composite propellants under high pressures is a crucial step for its application in high-pressure solid rocket motors.In this work,the combustion characteristics of AP/HTPB/Al composite propellants containing ferrocene-based catalysts were investigated,including the burning rate,thermal behavior,the local heat transfer,and temperature profile in the range of 7-28 MPa.The results showed that the exponent breaks were still observed in the propellants after the addition of positive catalysts(Ce-Fc-MOF),the burning rate inhibitor((Ferrocenylmethyl)trimethylammonium bromide,Fc Br)and the mixture of Fc Br/catocene(GFP).However,the characteristic pressure has increased,and the exponent decreased from 1.14 to 0.66,0.55,and 0.48 when the addition of Ce-FcMOF,Fc Br and Fc Br/GFP in the propellants.In addition,the temperature in the first decomposition stage was increased by 7.50℃ and 11.40℃ for the AP/Fc Br mixture and the AP/Fc Br/GFP mixture,respectively,compared to the pure AP.On the other hand,the temperature in the second decomposition stage decreased by 48.30℃ and 81.70℃ for AP/Fc Br and AP/Fc Br/GFP mixtures,respectively.It was also found that Fc Br might generate ammonia to cover the AP surface.In this case,a reaction between the methyl in Fc Br and perchloric acid caused more ammonia to appear at the AP surface,resulting in the suppression of ammonia desorption.In addition,the coarse AP particles on the quenched surface were of a concave shape relative to the binder matrix under low and high pressures when the catalysts were added.In the process,the decline at the AP/HTPB interface was only exhibited in the propellant with the addition of Ce-Fc-MOF.The ratio of the gas-phase temperature gradient of the propellants containing catalysts was reduced significantly below and above the characteristic pressure,rather than 3.6 times of the difference in the blank propellant.Overall,the obtained results demonstrated that the pressure exponent could be effectively regulated and controlled by adjusting the propellant local heat and mass transfer under high and low pressures.

Same Recovery Level of Compressed Chinese Fir Wood Can Be Obtained Through Different Heating Fixation Pathways

The recovery of compression set (RS) of wood after dry heating or steam treatment mainly depends on the temperature and time of treatment. For quantitative elucidation, a graph of intermediate RS was built with temperature (T) and time (t) as coordinates. In this graph (abbreviated as T-t planum), a series of curves of RS were created. This leads to a conclusion that same RS can be obtained by numerous different pathways. Further research on pathway equivalency based on T-t planum indicates that a low RS of 10% can be achieved definitely by different combinations of time and temperature. However, the fixation mechanism varies at different temperatures. On the equivalent pathways of higher recovery, the influence of temperature must be taken into consideration. The actual routes must be somewhat modified to achieve an expected result. This makes it possible for us to work out a best fixation pathway among all the possibilities, to eliminate the impact of heat on the mechanical properties of wood.

Discrimination of pressed sesame oil:A comparison study of non-targeted UV spectral fingerprints combined with different chemometric methods

This study explores the utilization of various chemometric analytical methods for determining the quality of pressed sesame oil with different adulteration levels of refined sesame oil using UV spectral fingerprints.The goal of this study was to provide a reliable tool for assessing the quality of sesame oil.The UV spectra of 51 samples of pressed sesame oil and 420 adulterated samples with refined sesame oil were measured in the range of 200-330 nm.Various classification and prediction methods,including linear discrimination analysis(LDA),support vector machines(SVM),soft independent modeling of class analogy(SIMCA),partial least squares regression(PLSR),support vector machine regression(SVR),and back-propagation neural network(BPNN),were employed to analyze the UV spectral data of pressed sesame oil and adulterated sesame oil.The results indicated that SVM outperformed the other classification methods in qualitatively identifying adulterated sesame oil,achieving an accuracy of 96.15%,a sensitivity of 97.87%,and a specificity of 80%.For quantitative analysis,BPNN yielded the best prediction results,with an R^(2) value of 0.99,RMSEP of 2.34%,and RPD value of 10.60(LOD of 8.60%and LOQ of 28.67%).Overall,the developed models exhibited significant potential for rapidly identifying and predicting the quality of sesame oil.

Differential expression of miRNAs and mRNAs in the livers of largemouth bass Micropterus salmoides under heat stress

Global warming threatens freshwater ecosystems and compromises fish survival.To elucidate the role of miRNAs in the livers of heat stressed largemouth bass,juvenile fish was subject to heat stress under 37°C.Both mRNA-seq and miRNA-seq were conducted on the liver tissues under control and heat stress conditions.Differential gene expression analysis and enrichment analysis were performed on mRNA and miRNA expression profiles.A total of 406 differentially expressed genes(DEGs)were discovered,of which 212 were up-regulated and 194 were down-regulated.Most of the DEGs were significantly implicated in the regulation of“protein processing in endoplasmic reticulum”,“proteasome”,“steroid biosynthesis”,and“ornithine decarboxylase inhibitor activity”pathways.In addition,47 differentially expressed miRNAs(DEMs)were identified in largemouth bass livers under heat stress,including 21 up-regulated and 25 down-regulated miRNAs.A negatively regulated miRNA-mRNA network including 12 miRNAs and 19 mRNAs was constructed with DEMs involved in“protein degradation”,“calcium ion regulation”,“cell apoptosis”,and“lipid metabolism”.Moreover,this study indicated novel-miR-144 activated the IRE1 signaling pathway by targeting txndc5 to induce liver apoptosis in largemouth bass under heat stress.This study revealed the involvement of miRNA regulation in largemouth bass in response to heat stress.

Changes of Chemical Composition and Crystalline of Compressed Chinese Fir Wood in Heating Fixation

The changes in relative crystalline, chemical composition and internal structure of compressed Chinese fir wood after different heating fixations were found strictly related to fixation conditions. The compressed wood powders were fixed either by heating at different temperatures all resulting in a 10% recovery, or by incubating at 180 °C for different periods with subsequent recovery levels. Both X-ray diffraction and infrared absorption of those samples have been measured. Relative crystalline increases at early stage of heating fixation, and then decreased gradually. Hemicellulose and lignin decomposition were induced by the fixation process, especially at 180 °C, and lignin was degraded actively. Furthermore, absorbed water was lost after heating, but cellulose did not change markedly. Although different fixation pathways can result in the same recovery level, the major chemical reactions un- derlying them vary, which is consistent with the difference of fixation mechanisms.

Heat exposure impairs porcine oocyte quality with suppressed actin expression in cumulus cells and disrupted F-actin formation in transzonal projections

Background:Transzonal projections(TZPs)constitute a structural basis for the communication between the oocyte and its surrounding cumulus cells(CCs),which play critical roles in promoting the oocyte maturation.Previously we found that heat stress(HS)causes loss of TZPs in porcine cumulus-oocyte complexes(COCs)with decreased density of filamentous actin(F-actin).However,the time-course responses of F-actin and its monomeric actins(β-actin andγ-actin)during the in vitro maturation of oocytes remain unclear.Results:In this study,excised porcine ovaries were exposed to HS at 41.5°C for 1 h before COCs were isolated and matured in vitro for 44 h.HS significantly reduced oocyte quality,characterized by impaired cumulus expansion,delayed meiotic resumption and lower survival rate and polar body extrusion rate,as well as decreased expression of mitochondrial DNA-encoded genes and elevated mitochondrial reactive oxygen species concentration.Expression ofβ-actin andγ-actin in CCs increased gradually with oocytes maturation,which was significantly reduced in HS group,especially at 24 h and/or 44 h of in vitro maturation.By contrast,the number of TZPs and the fluorescence intensity of F-actin in zona pellucida decreased gradually during oocytes maturation,which were significantly reduced by HS at 24 h of in vitro maturation.Moreover,colocalization analyses revealed bothβ-actin andγ-actin contribute to the F-actin formation in porcine TZPs,and the colocalization of F-actin with GJ protein connexin 45 was significantly reduced in heat-exposed COCs.Conclusions:The results indicate that the suppression of actin expressions in CCs,which may lead to the F-actin unstabilization in TZPs,will subsequently contribute to the compromised quality of oocytes under HS.

Suppression of the m/n=2/1 tearing mode by electron cyclotron resonance heating on J-TEXT

Stabilization of tearing modes and neoclassical tearing modes is of great importance for tokamak operation.Electron cyclotron waves(ECWs)have been extensively used to stabilize the tearing modes with the virtue of highly localized power deposition.Complete suppression of the m/n=2/1 tearing mode(TM)by electron cyclotron resonance heating(ECRH)has been achieved successfully on the J-TEXT tokamak.The effects of ECW deposition location and power amplitude on the 2/1 TM suppression have been investigated.It is found that the suppression is more effective when the ECW power is deposited closer to the rational surface.As the ECW power increases to approximately 230 k W,the 2/1 TM can be completely suppressed.The island rotation frequency is increased when the island width is reduced.The experimental results show that the local heating inside the magnetic island and the resulting temperature perturbation increase at the O-point of the island play dominant roles in TM suppression.As the ECW power increases,the 2/1 island is suppressed to smaller island width,and the flow shear also plays a stabilizing effect on small magnetic islands.With the stabilizing contribution of heating and flow shear,the 2/1 TM can be completely suppressed.

The Expression Characteristics and Potential Functions of Heat Shock Factors in Diatom Phaeodactylum tricornutum

Heat shock transcription factor(HSF)are essential regulators of heat shock protein(HSP)gene expression in plants and algae,contributing to their resilience against biotic and abiotic stresses.However,the localization,structure,phylogenetic relationship,and characteristics of PtHSF genes in microalgae,especially in diatom Phaeodactylum tricornutum,remain largely unexplored.This study presents a comprehensive analysis of the PtHSF gene family in P.tricornutum.A genome-wide analysis identified 68 PtHSF genes,which were classified into two distinct subfamilies:traditional and untraditional.Motif and structure analyses revealed evidence of multiple duplication events within the PtHSF gene family.Expression profiling revealed diurnal patterns,with 34 genes being downregulated during the light period and upregulated during the dark period,while 19 genes exhibited the opposite pattern.These findings suggest that PtHSF genes may have specialized functions during the diurnal cycle and play a crucial role in maintaining cellular homeostasis in response to various stresses.Notably,PtHSF16,30,and 43 genes exhibited higher expression levels,suggesting their potential importance.This study provides a valuable foundation for future investigations into the specific functions of HSFs under different stress conditions and their regulatory mechanisms in P.tricornutum and other microalgae.

Microstructural evolution of equal channel angular pressed AZ91D magnesium alloy during semi-solid isothermal heat treatment

The microstructural evolution of AZ91D magnesium alloy processed by equal channel angular pressing during isothermal heat treatment at 570℃was investigated.The results indicated that the equal channel angular pressing followed by semi-solid isothermal heat treatment was an effective method to prepare semi-solid nondendritic slurry of AZ91D magnesium alloy.During this process,its microstructure change underwent four stages,the initial coarsening stage,the structure separation stage,the spheroidization stage and the final coarsening stage.The microstructural spheroidization effect was the best after being heated for 15 min for the alloy pressed for four passes,and the grain size was the smallest.With the further increase of heating time,the grain size and shape factor increased.When the heating time was kept constant,the grain size and shape factor decreased with the increase of pressing passes.

Optimal Pitch Size of a Biphilic Surface for Boiling Heat Transfer at Subatmospheric Pressures

To date,using biphilic surfaces is one of the most promising methods for enhancing heat transfer and critical heat flux during boiling simultaneously.However,most of studies on the effect of biphilic surfaces on boiling perfor-mance have been carried out under atmospheric pressure conditions.In this context,the issues of heat transfer enhancement and stabilization of the boiling process at subatmospheric pressures are particularly critical due to the interesting characteristics of boiling heat transfer and bubble dynamics at subatmospheric pressures and their practical significance including aerospace applications.This paper investigates the effect of the pitch size between hydrophobic spots on a biphilic surface on heat transfer and bubble dynamics during boiling at subatmospheric pressures(from 11.2 kPa up to atmospheric pressure).The data analysis using infrared thermography demonstrated that the maximum heat transfer rate was achieved on a surface with a uniform pitch size(6 mm)at all pressures.In this case,the heat transfer enhancement,compared a bare surface,reached 3.4 times.An analysis of the departure diameters of bubbles based on high-speed visualization indicated that the optimal configuration of the biphilic surface corresponds to the pitch size equal to the bubble departure diameter.Using high-speed visualization also demonstrated that an early transition to film boiling was evident for configurations with a very high density of hydrophobic spots(pitch size of 2 mm).

The Person Who Impressed Me Most

How time flies!I’m a little sad when I realize that I will graduate from junior high school in a few months.Luckily,I have some wonderful memories.The person who impressed me most was my friend.My English was bad before and I felt unhappy about it.So I told it to a girl called Mary,who was good at English.She was willing to help me and made friends with me.She taught me some useful ways to learn English.

The Thing that Impressed Me Most

Time flies like an arrow,and time lost never returns.In the past few years of my junior high school life,what impressed me most was running.At first,I didn’t like sports.I thought I was supposed to spend more time on school work than on exercise.But gradually,I found that running was not only good for my health,but also helped me relieve stress.When I opened my arms and stretched my legs on the playground,I was like a deer running in the field,which made me get a sense of belonging.

Cluster Analysis of Differentially Expressed Heat Stress Genes in Rat Jejunal Mucosal

[Objective] The aim was to study the heat stress mechanism of differen tially expressed genes in rat jejunal mucosal.[Method] Variable cluster analysis and cluster analysis of samples on the differentially expressed heat stress genes in rat jejunal mucosal were carried out with SAS software,and statistics of distribution of the differentially expressed genes on chromosomes were conducted.[Result] The differentially expressed genes were divided into seven categories,of which,the upregulated genes included three categories （i.e.：Category A：Hspa1a,Hspa1b,Hspb1,Hsph1,Dnaja4,Ahsa2 and P4ha1; Category B：Cyp1a2,Zbtb16,Gucy2g,Fgb,Cyp4a3 and Etv2; and Category C：Cyp1a2,Chac1 and Cyp4b1） and the down-regulated genes included four categories （i.e.：Category D：Tlr2,Noxo1,LOC286989 and Aspg; Category E：RGD1560395,Alb and BQ194726; Category F：Ccl4,Gzmk,Al228153,Anxa10,S100a9 and Ascl5; and Category G：Reg1a and Slc13a1）.The classification,function and reasons of differential expression for each gene category were analyzed.[Conclusion] Most of the three categories of up-regulated genes were related to the heat shock proteins; and most of the four categories of down-regulated genes were related to the immunity,providing reference for discussion of the heat stress mechanism.

Flow and Heat Transfer Features of Supercritical Pressure CO_(2) in Horizontal Flows under Whole-Wall Heating Conditions

Based on the first and second laws of thermodynamics,the heat transfer and flow(thermohydraulic)characteristics of horizontal supercritical pressure CO_(2)(S-CO_(2))in a circular pipe under heating conditions were investigated numerically.Heating flows in two different diameters(d)of 4 and 6 mm were simulated in pipes with pressures of 8 MPa,mass fluxes(G)of 300 and 400 kg/(m^(2)·s),and heat fluxes(q)of 50,75 and 100 kW/m^(2).In the d=4 mm pipe,the peak heat transfer coefficient(hb)was about 3 times higher than in the d=6 mm pipe,while the entropy production due to fluid friction in the 4 mm pipe was on average 1.1 times higher,and the entropy production due to heat transfer was on average about 67%lower.A 4 mm tube was employed to further evaluate the influence of the applied wall heat flux,the results demonstrated that the irreversibility due to heat transfer was on average more than 4 times higher when heat flux density was 100 kW/m^(2)than when the heat flux density was 50 kW/m^(2),while the peak of heat transfer coefficient increased by 1.4 times as q was decreased from 100 to 50 kW/m^(2).The effect of thermal acceleration was ignored,while the buoyancy effect resulted in secondary flow and significantly affected the flow and heat transfer features.The jet flows were found in the vicinity of the lower wall of the pipe,which made the two fields of velocity and temperature gradient more synergistic,leading to an enhancement in heat transfer in the vicinity of the upper wall.The aggravation of heat transfer resulted in high irreversibility of heat transfer in the cross-sectional area near the wall,while the local friction irreversibility was less affected by the buoyancy effect,and the distribution was uniform.The uneven distribution of thermophysical properties also confirmed that the enhanced heat transfer occurred near the wall area at the bottom of the pipe.

Analysis of differentially expressed genes in the sea cucumber Apostichopus japonicus under heat stress

The sea cucumber Apostichopus japonicus plays important roles in marine benthic ecosystem as environmental cleaners,and it is the important aquaculture species in China.High water temperature poses critical threat for the survival of A.japonicus,which has resulted in extensive death in summer.To explore the genes expression profiles under different levels of heat stress,the high-throughput RNA-seq was applied in this study.Our results revealed a total of 1371,1225 and 1408 differentially expressed genes(DEGs)in 26℃for 6 h,26℃for 48 h and 30℃for 6 h respectively in comparison with Control group.The pathway analysis suggested“Protein processing in endoplasmic reticulum(ER)”was significantly enriched in all these heat stress(HS)treatment groups.The expression results of key DEGs in this pathway(Hsp70,Derlin,NEF,PDI,GPR94 and ERP57)by qRT-PCR was in accordance with the RNA-seq data.The subcluster analysis of DEGs revealed that a variety of heat shock proteins(HSPs)and calcium ion binding proteins had an obvious up-regulated expression in 26℃for 6 h,comparatively low expression in 26℃for 48 h,and the highest expression in 30℃for 6 h.The other DEGs subcluster,consisting of critical components of extracellular matrix(ECM)and a subset of peptidases and proteases,showed significantly rising tendency in 30℃for 6 h.Additionally,the expression of matrix metalloproteases(MMP1,MMP16 and MMP19)was prominently affected by HS,and peaked in 30℃for 6 h.This study provides a series of candidate genes for further study about heat shock response in A.japonicus,especially genes associated with protein processing in ER and regulation of ECM,which also offers new insights into cellular homeostasis under stressful conditions in marine invertebrates.

Effects of Heat Clearing and Stasis Resolving Method on PTS,Inflammatory Factors and T-lymphocyte Subsets in Peripheral Blood of URM Patients with Suppressed Internal Heat

[Objectives]To explore the effects of heat clearing and stasis resolving method on prethrombotic state,inflammatory factors and T-lymphocyte subsets in peripheral blood of unexplained recurrent miscarriage(URM)patients with suppressed internal heat.[Methods]Thirty cases of URM patients with suppressed internal heat and 30 normal women were collected,and characteristics of changes in peripheral serum D-dimer(D-D),fibrin degradation product(FDP),fibrinogen(FIB),IL-6,IL-10 and TNF-α,CD,CD,CD,CD,CDlevels were detected.URM patients were treated with traditional Chinese medicine for clearing heat and resolving blood stasis for 3 menstrual cycles,and the changes of indicators before and after treatment were observed.[Results]Compared with normal women,the peripheral serum levels of D-D,IL-6,TNF-αand CDin URM patients with suppressed internal heat were increased(P<0.05),while the IL-10 lymphocyte level was significantly decreased(P<0.05);compared with that before treatment,the contents of D-D,IL-6,TNF-αand CDdecreased after 3 menstrual cycles(P<0.05),while the contents of IL-10 and CDT lymphocytes increased significantly(P<0.05).[Conclusions]The heat clearing heat and stasis resolving method can effectively improve the prethrombotic state of URM,and the action mechanism may be related to the regulation of immune and peripheral blood inflammatory factors.

Constitutively Expressed αB—Crystallin in Heat Schock Transcription Factor 1 Knockout Mice Myocardium

Objective-To investigate the effects of heat shock transcription factor 1) gene on the constitutivety expressed αB-CrystaUin (aBC) in mice myocardium. Methods-The expression levels of constitutive aBC in HSF1 knockout (hsf1 - /- ) and HSFl wild type (As/1 + /+) mice myocardium were evaluated by western blot and immunohistochemistry. Results : The αBC levels in hsfl -/- and hsfl +/+ were 68. 42±4. 16, 100. 00±7. 58, respectively (P<0. 05, cytoso-lic fraction) , and 20. 53±1. 01, 37. 55±1. 91, respectively (P<0. 05, pellet fraction). The aBC signals decreased significantly in hsfl -/- myocardium when compared with those in hsfl +/+ myocardium stained with fluorescence immunohistochemistry. Conclusion-HSF1 is an important, but not the only factor, which mediates the constitutively expressed aBC.

Microstructural evolution of 2026 aluminum alloy during hot compression and subsequent heat treatment

2026 aluminum alloy was compressed in a temperature range of 300-450 ℃ and strain rate range of 0.01-10 s^-1. The correlation between compression conditions and microstructural evolution after solution and aging heat treatment was investigated. It is found that the recrystallization and precipitation behavior after heat treatment are associated with the temperature compensated strain rate Z value during hot deformation. Under low Z parameter condition, a small quantity of free recrystallized grains are formed, and the well formed subgrains with clean high-angle boundaries and coarse precipitates seem to be remained during heat treatment. Under high Z parameter condition, a large number of fine equiaxed recrystallized grains are produced, and a high dislocation density with poorly developed cellularity and considerable fine dynamic precipitates are replaced by the well formed subgrains and relatively coarse precipitates after heat treatment. The average recrystallized grain size after heat treatment decreases with increasing Z value and a quantitative relation between the average grain size and the Z value is obtained.

Microstructure evolution and thermal expansion of Cu-Zn alloy after high pressure heat treatment

The thermal expansion coefficients of Cu-Zn alloy before and after high pressure treatment were measured by thermal expansion instrument in the temperature range of 25？700 ℃,and the microstructure and phase transformation of the alloy were examined by optical microscope,X-ray diffractometer（XRD） and differential scanning calorimeter（DSC）.Based on the experimental results,the effects of high pressure treatment on the microstructure and thermal expansion of Cu-Zn alloy were investigated.The results show that the high pressure treatment can refine the grain and increase the thermal expansion coefficient of the Cu-Zn alloy,resulting in that the thermal expansion coefficient exhibits a high peak value on the α-T curve,and the peak value decreases with increasing the pressure.

INFLUENCE OF HEAT TREATMENT ON THE COMPRESSIVE STRESS EFFECT OF MAGNETOSTRICTION OF <112> AXIAL ALIGNED Tb-Dy-Fe ALLOYS

The magnetostrictive properties of <112> axial aligned Tb0.3Dy0.7(Fe1-xMx)1.95(M=Mn, Al, x=0～ 0.15) alloys prepared by directional solidification are reported. The influence of heat treatment on microstructure and the compressive stress effect of magnetostriction is discussed.